Cysts, Glandular Lesions, and Others


Anogenital mammary-like glands1

Sweat glands1

Hair follicles and sebaceous glands1

Bartholin glands

Minor vestibular glands

Paraurethral (Skene) gland

Mesonephric duct remnants

Cloacogenic remnants

Endometriosis


1See Chap. 11





Bartholin Gland


In 1677, Caspar Secundus Bartholin, a Dutch anatomist, described the major vestibular glands [1]. The Bartholin gland is a bilateral, round-to-oval gland measuring about 1 cm in diameter (hence the term major vestibular gland compared to small minor vestibular glands) which drains through a 2.5 cm duct that opens into the vestibule, exterior and adjacent to the hymen in a posterolateral location (at the 4:00 and 8:00 of the vulvar vestibule). After the age of 30, the gland gradually involutes [2] (see Chap. 1). Normal histology of the gland is that of acini lined by columnar mucus-secreting cells surrounded by a peripheral layer of myoepithelial cells. The Bartholin duct is lined by transitional-like epithelium in its proximal part, but at the vestibular surface, the lining is nonkeratinized squamous epithelium (Fig. 12.1). Cystic lesions and inflammations are the most common benign causes of swelling of the Bartholin gland. Although rare, benign lesions, such as nodular hyperplasia and adenoma, and malignant lesions, including carcinomas, are the most common tumors arising at the posterolateral aspect of the vestibule [311].

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Fig. 12.1
Bartholin gland. Mucous acini and columnar and transitional lining of the duct are seen


Bartholin Gland Cyst and Mucous Cyst


Using magnetic resonance imaging studies of 430 asymptomatic women, the incidence of Bartholin gland cysts has been determined to be approximately 3 % [12]. In a study of 104 Bartholin glands from 103 patients, 84.6 % of cases had retention cysts (blockage of duct with retention of secretions leading to secondary cyst formation), abscesses in 10.6 %, endometriosis in 2 %, and neoplasms in 3 % [13]. Bartholin gland cyst results from dilatation of the Bartholin duct due to obstruction. The majority of these cysts are seen in women in reproductive age, most frequently in the third decade. The characteristic clinical presentation consists of an asymptomatic unilateral soft cystic or firm nodule of variable size. Large cyst can affect the labia majora and even extend upward and simulate an inguinal hernia or a cyst of the canal of Nuck. Tenderness and discomfort are complains when the lesions are large or infected. A recent meta-analysis of 24 studies, each with 14–200 patients with Bartholin duct cyst or abscess, identified multiple treatment modalities including silver nitrate ablation, cyst excision, carbon dioxide laser, marsupialization, needle aspiration, fistulization, and incision and draining; yet the analysis failed to identify the best treatment form [14].


Histologic Features


Squamous, transitional, ciliated, or mucous epithelium lines the cyst. Any combination of the above epithelial types can be encountered (Fig. 12.2a, b). Areas resembling the fallopian tube epithelium or apocrine-type secretion can rarely be seen. Preexisting Bartholin gland tissue is often detected in the vicinity of the cyst [15, 16]. Nearly half of the retention cysts had variable degrees of inflammation [13]. Co-occurrence with endometriosis has been reported [17]. Association with human papilloma virus (HPV) has been reported even with the development of high-grade squamous intraepithelial neoplasia [18, 19]. Melanin pigment and melanocytes in the cyst wall were documented in an extraordinary case [20].

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Fig. 12.2
Bartholin gland cyst. (a) A combination of squamous, transitional, and mucous epithelium is seen lining the wall of the cyst. (b) Transitional epithelium at high magnification


Differential Diagnosis


Mucous cysts, likely resulting from occlusion of minor vestibular glands, are smaller cysts containing mucinous and squamous cells. It is likely that some of the so-called mucinous and ciliated cysts of the vulva in fact represent the Bartholin gland cyst. Location is the main discriminant of these lesions. Epidermoid cyst, most frequently located in the labia majora, is lined by stratified squamous epithelium and contains white-yellowish grumous content. Mesonephric-like or Gartner cyst can be differentiated from Bartholin gland cyst by its location in the lateral aspect of the vulva and lining by low columnar nonmucinous epithelium. Cyst of the canal of Nuck, also called mesothelial cyst, can be distinguished from Bartholin gland cyst by its position in the superolateral portion of the labia majora and lining by flattened mesothelial cells.


Summary





  • Clinical Presentation



    • Commonly affect women of reproductive age


    • A soft and cystic nodule of variable size


  • Histologic Features



    • A cyst lined by squamous, transitional, ciliated, or mucous epithelium


  • Differential Diagnosis



    • Mucinous cyst


    • Ciliated cyst


    • Epidermoid cyst


    • Mesonephric-like or Gartner cyst


    • Cyst of the canal of Nuck


Takeaway Essentials





  • Clinical Relevant Pearls



    • Most frequent vulvar cyst.


    • Location is the most discriminative diagnostic factor.


    • The majority of these cysts are asymptomatic.


  • Pathology Interpretation Pearls



    • Any combination of squamous, transitional, ciliated, or mucous epithelium can be seen lining the cyst.


    • Presence of residual mucinous glands around the cysts is an important diagnostic clue.


Nodular Hyperplasia


Nodular hyperplasia is a rare and benign lesion of the Bartholin gland presenting clinically as an asymptomatic or slightly painful nodular lesion measuring up to 4–5 cm [6, 2125]. The ages of the patients ranged from 19 to 56 years [6, 23]. Nodular hyperplasia might be more common than reported since most are often misdiagnosed as cysts clinically; thus, incision and drainage is done rather than excision [2123]. For cases with incomplete excision, follow-up has not demonstrated recurrence [23]. Dyspareunia and vulvar vestibulitis are rare associations [24, 26]. Since nodular hyperplasia is frequently associated with inflammation and duct obstruction, some have speculated that these may be the inciting factors for the hyperplastic proliferation.


Histologic Features


Grossly, these lesions are multilobular, nonencapsulated, tan to gray in color, and up to 4–5 cm in greatest dimension [6, 22, 23]. It is a well-circumscribed and lobular lesion with an increased number of secretory acini maintaining a normal duct-acinar relationship (Fig. 12.3). The individual acini are composed of cuboidal or columnar cells, with copious, pale, mucin-filled cytoplasm and bland, basally located nuclei resting on a peripheral layer of attenuated myoepithelial spindled cells. A sparse lymphohistiocytic infiltrate, squamous metaplasia of the ducts, and extravasated stromal mucin can be seen [6, 22, 23].

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Fig. 12.3
Nodular hyperplasia of Bartholin gland. Although there are an increased number of secretory acini maintaining, a normal duct-acinar relationship is maintained

By immunohistochemistry, all ten cases of Bartholin gland hyperplasia in Santos et al.’s series (2006) were positive for keratins AE1/AE3, CAM5.2, and high molecular weight epithelial membrane antigen (EMA) and polyclonal carcinoembryonic antigen (CEA). These lesions in Santos and Koenig’s series were negative for estrogen receptor (ER) and progesterone receptor (PR), with a low Ki-67 proliferation index [6, 23]. Smooth muscle actin (SMA) highlights the periacinar myoepithelial cells.

Clonality analysis by HUMARA was demonstrated to be clonal in one case, suggesting that these lesions could be neoplastic rather than hyperplastic [22].


Differential Diagnosis


Lesions similar to nodular hyperplasia were reported as “Bartholin gland adenoma” or adenoma of minor vestibular glands resulting in confusion [4, 7, 27]. The proliferation of mucinous acini in nodular hyperplasia would maintain the lobular architecture and duct-acinar relationship and lacks encapsulation with irregular outline, whereas adenoma would be characterized by a sharply circumscribed and encapsulated yet haphazard proliferation of glands and acini without the normal duct-acinar arrangement [4, 6, 7, 27].


Summary





  • Clinical Presentation



    • Solitary nodule


  • Histologic Features



    • Unencapsulated proliferation with irregular borders


    • Increased number of secretory acini maintaining a normal duct-acinar relationship and lobular architecture


  • Differential Diagnosis



    • Normal Bartholin gland


    • Bartholin gland adenoma


Takeaway Essentials





  • Clinical Relevant Pearls



    • Most Bartholin gland hyperplasia lesions are often misdiagnosed as cysts clinically.


  • Pathology Interpretation Pearls



    • Bartholin gland hyperplasia contains an increased number of acini yet with a preserved duct-to-acinar ratio.


  • Immunohistochemical/Molecular Findings



    • Estrogen receptor negative, progesterone receptor negative, and low Ki-67 proliferation index.


    • Smooth muscle actin highlights the periacinar myoepithelial cells.


Bartholin Gland Adenoma and Adenomyoma


Both lesions are extremely rare. There have been approximately ten cases of Bartholin gland adenoma and only one case of adenomyoma reported in the literature [3, 57, 28, 29]. These are often well-circumscribed and solid lesions, up to 2.5 cm in greatest dimension [6].


Histologic Features


Bartholin gland adenoma, as defined by Koenig and Tavassoli [6], represents a compact, well-circumscribed, encapsulated lobular proliferation of small bilayered tubuloductular structures with intraluminal colloid-like secretions contiguous with identifiable Bartholin gland structures. There is a lack of normal duct-acinar arrangement. Bartholin gland adenomyoma is a well-circumscribed tumor composed of tubuloglandular components and a fibromuscular stroma positive for SMA and desmin [6]. In comparison to adenoma, adenomyoma would have less glandular elements and a prominent fibromuscular stroma that is immunoreactive for both smooth muscle actin and desmin.


Differential Diagnosis


The main differential diagnosis would be Bartholin gland nodular hyperplasia which would lack a capsule and yet maintain the duct-acinar relationship [6].


Summary





  • Clinical Presentation



    • Solitary vulvar mass, well circumscribed and solid


  • Histologic Features



    • Adenoma: an encapsulated yet haphazard proliferation of glands and tubules/duct without the normal duct-acinar arrangement


    • Adenomyoma: less glandular elements and a prominent fibromuscular stroma


  • Differential Diagnosis



    • Bartholin gland nodular hyperplasia


Takeaway Essentials





  • Clinical Relevant Pearls



    • Both lesions are extremely rare.


  • Pathology Interpretation Pearls



    • For both adenoma and adenomyoma, there is a lack of normal duct-acinar arrangement.


  • Immunohistochemical/Molecular Findings



    • Fibromuscular stroma of adenomyoma would be immunoreactive for smooth muscle actin and desmin.


Bartholin Gland Carcinomas


Bartholin gland carcinomas account for 1 % of all female genital tract malignancies and 2–7 % of vulvar carcinomas [30]. This may be an overestimation if strict criteria are applied [3133]. These include (1) presence of areas of apparent transition from normal to neoplastic elements, (2) involvement of areas of the Bartholin gland and origin histologically compatible from the gland, and (3) no evidence of a concurrent primary tumor elsewhere [34]. Although the first criterion is the most reliable, it can only be identified in less than half of the tumors in reviewed series of these tumors, especially in large tumors.

In general primary adenocarcinoma of the Bartholin gland is a slow-growing tumor with marked tendency for perineural and local invasion. The main clinical complaint is itching and burning sensation that are caused by pressure from a palpable mass present in the posterior part of the labium majorus. Bartholin gland carcinoma frequently metastasizes to the inguinal-femoral lymph nodes in advanced disease. Radical vulvectomy and wide local excision with inguinal lymph node dissection are the main treatment methods. Currently, chemotherapy and radiation have not been shown to improve survival [35]. The overall 5-year survival has been reported to be 71–84 %; however, the 5-year survival drops to 18 % with multiple lymph node involvement [35]. It appears that the stage of the disease will define the prognosis over the histologic type of tumor [33].


Histologic Features and Differential Diagnosis


The most common histologic subtypes are squamous cell carcinoma and adenocarcinoma occurring with an approximately equal frequency and together accounting for up to 90 % of Bartholin gland carcinoma [3641] (Table 12.2).


Table 12.2
Histologic types of Bartholin gland carcinomas

























Squamous cell carcinoma

Adenocarcinoma

Clear cell adenocarcinoma

Adenoid cystic carcinoma

Polymorphous low-grade adenocarcinoma

Salivary gland-type basal cell adenocarcinoma

Low-grade epithelial-myoepithelial carcinoma

Transitional cell carcinoma

Neuroendocrine/Merkel cell carcinoma

Lymphoepithelioma-like carcinoma


Squamous Cell Carcinoma

The lining of the Bartholin gland duct at the vestibular orifice changes from transitional to squamous epithelium, and from this transition zone, squamous cell carcinoma would arise. A painless mass is the most common clinical presentation [10]. The histology is similar to any squamous cell carcinoma characterized by keratin pearl formation and neoplastic cells with keratinization (Fig. 12.4a, b). The association of squamous cell carcinoma of Bartholin gland and HPV, especially HPV16, has been established [42].

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Fig. 12.4
Bartholin gland squamous cell carcinoma. (a) An in situ component is seen arising from the Bartholin gland duct. (b) Full-thickness dysplasia with keratinization is seen


Adenocarcinoma

Histologic sections show a carcinoma with glandular architecture. The tumor cells have abundant cytoplasm and peripheral hyperchromatic nuclei (Fig. 12.5a, b). They are ER and PR positive and negative for CK20, CK7, CDX2, mammaglobin, and Her2/neu. Rare case of primary adenocarcinoma of the right labium minus has given rise to bone metastasis [43]. Rarely the adenocarcinoma would be comprised of clear neoplastic cells [40]. In this instance, a metastatic clear cell adenocarcinoma from the kidney or ovary needs to be excluded.

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Fig. 12.5
Bartholin gland adenocarcinoma. (a) A proliferation of strands and nests of epithelial neoplastic cells are seen associated with a mucinous background. (b) The tumor cells are polygonal and with prominent nucleoli


Adenoid Cystic Carcinoma

Salivary gland-type carcinomas rarely arise from the Bartholin gland, and they most commonly are adenoid cystic carcinoma [4456], combined adenoid cystic and squamous cell carcinoma [57], polymorphous low-grade adenocarcinoma [58], salivary gland-type basal cell adenocarcinoma [59], and low-grade epithelial-myoepithelial carcinoma [60].

Adenoid cystic carcinoma of the vulva is a rare tumor [4456], and one must exclude the possibility of metastasis before rendering the diagnosis of primary adenoid cystic carcinoma of the vulva. Some do consider that adenoid cystic carcinoma can arise from anogenital mammary-like glands [61]. The sizes of the tumor range from 0.5 to 4 cm [50]. The clinical presentation can be nonspecific including pain, burning sensation, palpable mass, or pruritus; and it is frequently misdiagnosed and treated as an infected Bartholin gland or cyst [62]. The treatment often includes local excision and radical vulvectomy, with or without regional lymph node dissection [55]. The overall survival is excellent with the 5-year and 10-year survival rates being 47–83 % and 33–38 %, respectively [50]. The bone and lung are the most common sites of metastasis; and the liver, kidney, and brain are less frequently involved sites [56].

Histopathologically, the growth pattern can be cribriform, tubular, solid, or a combination of these (Fig. 12.6). Perineural invasion is a common histologic feature which accounts for the frequent recurrence. In their series of 17 cases, Milchgrub et al. [56] reported that the histologic pattern, whether classical, tubular, or mixed, did not predict survival. CD117 expression is noted in invariably all adenoid cystic carcinomas [63]. MYB immunostain has recently been reported to be specific for adenoid cystic carcinoma although the sensitivity is only 65 % [64] (see Vignette 1 at the end of this chapter).

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Fig. 12.6
Adenoid cystic carcinoma. A cribriform architecture is noted


Other Salivary Gland-Type Carcinomas

Basal cell adenocarcinoma of the salivary gland is a low-grade neoplasm showing myoepithelial differentiation. There has been one rare case with similar histology reported in the vulva [59]. Tumor lobules with peripheral palisade were comprised of two types of cells. The small and basaloid cells at the periphery had a myoepithelial phenotype and were SMA and calponin positive. The inner cells had abundant amphophilic cytoplasm and were positive for keratin CAM5.2 and 34betaE12 [59]. The lack of epidermal connection and the myoepithelial phenotype are helpful distinguishing features from an adenoid basal cell carcinoma. Squamous differentiation, which can be seen in basal cell adenocarcinoma, is typically absent in the solid variant of adenoid cystic carcinoma.

Similarly, in two cases of low-grade epithelial-myoepithelial carcinoma reported by McCluggage et al. [60], normal Bartholin gland tissue was seen at the periphery. Tubular, trabecular, and insular patterns were comprised of outer myoepithelial cells (p63+, calponin+, SMA+) and inner cuboidal epithelial cells (broad-spectrum keratin+, EMA+). Both cases were strongly positive for CD117.


Transitional Cell Carcinoma

Rare cases of transitional cell carcinomas have been reported originating from the duct of Bartholin glands [6567]. A progression from low-grade dysplasia to invasive transitional cell carcinoma was described in the case report by Fujiwaki [67]. The transitional cell carcinoma of Bartholin gland would have similar histologic features as noted in transitional cell carcinomas of other sites.


Neuroendocrine or Merkel Cell Carcinoma

Neuroendocrine carcinoma or Merkel cell carcinoma can rarely involve the vulvar skin and arise from the Bartholin gland [6870]. Clinically, it can mimic a Bartholin gland abscess [71]. Histologically, a tumor is composed of neoplastic cells with scant cytoplasm and granular chromatin, frequent mitotic figures, and apoptotic bodies (Fig. 12.7a). The neoplastic cells express cytokeratin 20 in a perinuclear dot-like pattern (Fig. 12.7b) and exhibits positivity for wide-spectrum and low molecular weight cytokeratins, EMA, and neuroendocrine markers including chromogranin, synaptophysin, and neuron-specific enolase [72]. The differential diagnosis would include a metastatic small cell carcinoma from other sites.

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Fig. 12.7
Merkel cell carcinoma. (a) The neoplastic cells have scant cytoplasm, granular nuclear chromatin, frequent mitotic figures, and apoptotic bodies. (b) Cytokeratin 20 demonstrates dot-like perinuclear positivity


Lymphoepithelioma-Like Carcinoma

In the four reported cases of lymphoepithelioma-like carcinoma of the vulva [7376], syncytial sheets of epithelial cells of variable shapes were infiltrated by a notable number of lymphocytes and plasma cells. The tumor cells had large nuclei, vesicular chromatin, and prominent nucleoli. In one case, a transition from neoplastic cells to Bartholin gland acini was seen [73]. The tumor cells expressed epithelial markers including keratins AE1/AE3 and epithelial membrane antigen [73]. CD3 and CD20 demonstrated a mixed infiltrate of T and B lymphocytes within the associated inflammatory infiltrate [73]. The association with Epstein-Barr virus as in undifferentiated carcinoma of other sites has not been documented for these tumors from the vulva [7375].


Summary





  • Clinical Presentation



    • A slow-growing tumor with marked tendency for perineural and local invasion.


    • The main clinical complaint is itching and burning sensation.


  • Histologic Features



    • The most common histologic subtypes are squamous cell carcinoma and adenocarcinoma.


    • Adenoid cystic carcinoma is the most common from the salivary gland-type carcinomas arising in Bartholin gland.


  • Differential Diagnosis



    • Metastatic carcinoma to Bartholin gland


Takeaway Essentials





  • Clinical Relevant Pearls



    • A clinically diagnosed Bartholin gland cyst refractory to treatment needs to be biopsied to rule out a carcinoma, especially in a postmenopausal woman.


    • It appears that the stage of the disease will define the prognosis over the histologic type of tumor.


  • Pathology Interpretation Pearls



    • Criteria for diagnosing primary carcinoma of Bartholin gland: (1) presence of areas of apparent transition from normal to neoplastic elements, (2) involvement of areas of the Bartholin gland and origin histologically compatible from the gland, (3) no evidence of a concurrent primary tumor elsewhere


  • Immunohistochemical/Molecular Findings



    • Bartholin gland carcinoma is typically ER+ and PR+.


    • Although specific, MYB immunostain is detected in only 65 % of adenoid cystic carcinomas.


Other Lesions of Bartholin Gland


Bartholin gland may rarely be secondarily involved by neoplastic cells in extramammary Paget disease or melanoma, display metaplastic changes (squamous, apocrine, or intestinal metaplasia) in long-standing inflammatory processes of the vulva, and show alterations resembling those seen in salivary glands in necrotizing sialometaplasia.


Paraurethral (Skene) Gland Cyst and Prostatic-Type Tissue of the Vulva


The skene gland is a paired organ located on either side of the urethral meatus, representing the female homologue of the male prostate. Paraurethral gland cyst results from cystic dilatation of the duct of the gland. This 1–2 cm-sized lesion is asymptomatic and involves the upper lateral introitus [77, 78].

There have been three cases of prostatic-type tissue involving the vulva reported in the literature [79, 80]. The ages of these patients ranged from 43 to 54 years [79, 80]. The lesion appeared as intermittent pea-sized bilateral swellings next to or near the urethral meatus which occasionally discharged pus-like material. It has been speculated that these benign lesions are derived from the Skene glands and misplaced during embryologic development [80].


Histologic Features


The skene gland is comprised of two layers of epithelium with the outer being columnar and contains eosinophilic secretion (Fig. 12.8a, b). Skene gland cyst is derived from the duct, and the wall is lined by either transitional or stratified squamous epithelium with rare mucinous cells (Fig. 12.9a, b). In the case of prostatic-type tissue of the vulva, there are small lobular clusters of benign glands within the superficial dermis, focally in continuity with the base of the epidermis, lined by a double-layered epithelium containing PAS-positive bright, eosinophilic cytoplasmic granules in some of the luminal cells, resembling Paneth cell-like change (Fig. 12.10a, b). The glands are positive for prostate-specific antigen (PSA) and prostatic acid phosphatase (PAP) [79, 80].

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Fig. 12.8
(a, b) Skene gland. Two layers of epithelium and eosinophilic secretion are seen


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Fig. 12.9
(a, b) Skene gland cyst. Derived from the duct, the lining of the cyst is comprised of stratified squamous epithelium


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Fig. 12.10
(a, b) Prostatic-type tissue of the vulva. Lobular clusters of benign glands within the superficial dermis lined by a double-layered epithelium (Courtesy of Colin J.R. Stewart, FRCPA, Perth, Western Australia, Australia)


Differential Diagnosis


Skene gland hyperplasia (analogous to benign prostatic hyperplasia in male) (Fig. 12.11a, b) and adenocarcinoma are rare entities [81, 82]. The adenocarcinomas presented as periurethral masses and are associated with elevated preoperative serum PSA level [83]. The tumor cells are also positive for PSA and PAP immunostains [84]. Urethral diverticula are lined also by transitional epithelium originating from the lower segment of the urethra, and only clinical findings and imaging are able to separate these diseases.

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Fig. 12.11
Hyperplasia of paraurethral Skene glands. (a) Hyperplasia of the glandular as well as the stromal components is seen similar to prostatic hyperplasia. (b) The glandular epithelium expresses prostatic acid phosphatase (×100)


Summary





  • Clinical Presentation



    • Prostatic-type tissue of the vulva: intermittent and bilateral swellings near or at the urethral meatus


  • Histologic Features



    • The wall of Skene gland cyst is comprised of transitional or stratified squamous epithelium with rare mucinous cells.


    • Prostatic-type tissue of the vulva: small lobular clusters of benign glands, with double-layered epithelium, within the superficial dermis.


  • Differential Diagnosis



    • Skene gland hyperplasia


    • Urethral diverticula


Takeaway Essentials





  • Clinical Relevant Pearls



    • Skene gland represents the female homologue of the male prostate.


    • The adenocarcinomas arising from Skene gland are associated with elevated preoperative serum prostatic specific antigen level.


  • Pathology Interpretation Pearls



    • Prostatic-type tissue of the vulva: small clusters of benign glands are lined by a double-layered epithelium containing PAS-positive bright, eosinophilic cytoplasmic granules in some of the luminal cells, resembling Paneth cell-like change.


  • Immunohistochemical/Molecular Findings



    • The ectopic prostatic glands are positive for prostate-specific antigen and prostatic acid phosphatase.


Cyst of the Canal of Nuck (Mesothelial Cyst)


The cyst of the canal of Nuck, also known as hydrocele of the canal of Nuck, was first described in 1691 by the Dutch anatomist Anton Nuck [85]. The canal of Nuck is a cystic remnant of the processus vaginalis peritonei representing a rudimentary sac of peritoneal mesothelium carried down by the round ligament as it passes through the inguinal canal and inserts into the labium majus [86]. Failure in obliteration of this structure during the first year of life results in blockage and cystic dilatation [87]. Three types of cyst of the canal of Nuck have been reported: (1) the type that does not have patency between the cyst and peritoneal cavity, (2) the type with patency, and (3) the “hourglass type” that consisted of two cysts with the proximal one connected to the peritoneal cavity [88].

Patients, usually girls or young women, present with an asymptomatic, nontender swelling (average of 3 cm, up to 7 cm) in the groin or, rarely, with a mass in the labium majus or mons pubis. Clinically, these lesions are commonly mistaken for inguinal hernia [89, 90]. Anecdotal cases of endometriosis and ectopic pregnancy developed in association with the cyst of the canal of Nuck have been reported [9193]. Aspiration of the cyst causes recurrence; thus, surgical excision and ligation of the neck of processus vaginalis is the standard treatment [88].


Histologic Features


The wall of the cyst is lined by low cuboidal cells and surrounded by loosely cellular fibrous tissue. The epithelium is of mesothelial origin; thus, it is immunoreactive for calretinin and D2-40. Stromal fibrosis and hemosiderin deposition can be seen.


Differential Diagnosis


The clinical differential diagnosis includes round ligament cysts, varicosities of the round ligament, inguinal herniation of the ovary, epidermoid cyst, and abscesses. Definitive diagnosis can be made with ultrasonography or MRI [90, 92, 94].


Summary





  • Clinical Presentation



    • An asymptomatic and nontender mass in the labium majus or mons pubis


  • Histologic Features



    • The wall of the cyst is lined by low cuboidal cells and surrounded by loosely cellular fibrous tissue.


  • Differential Diagnosis



    • Inguinal hernia


Takeaway Essentials





  • Clinical Relevant Pearls



    • Equivalent of the hydrocele in males.


    • Definitive diagnosis can be made with ultrasonography or magnetic resonance imaging.


    • Aspiration of the cyst causes recurrence; thus, surgical excision is the treatment of choice.


  • Pathology Interpretation Pearls



    • The epithelium is of mesothelial origin.


  • Immunohistochemical/Molecular Findings



    • The epithelial cells are positive for calretinin and D2-40.


Mesonephric-Like Cyst and Ciliated Cyst


Mesonephric-like (mesonephric Gartner) cyst is a rare cystic lesion of presumed mesonephric/Wolffian origin that involves the lateral aspect of the vulva and vagina and manifests itself as a thin-walled, translucent cyst containing clear fluid [95]. Ciliated cyst of the vulva is a rare lesion that has been reported in association with Stevens-Johnson syndrome, chronic inflammation, and 5FU therapy [96].


Histologic Features


The wall of a mesonephric-like or Gartner cyst is lined by cuboidal to columnar non-ciliated epithelium (Fig. 12.12a, b), whereas the ciliated cyst is lined by tubal- or endometrial-type epithelium (Fig. 12.13a, b). The ciliated cyst of the vulva can be distinguished from endometriosis by the lack of endometrial-type stroma.

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Fig. 12.12
(a, b) Gartner or mesonephric-like cyst. The wall is comprised of simple cuboidal or low columnar epithelium


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Fig. 12.13
(a, b) Ciliated cyst. The cyst is lined by ciliated columnar epithelium


Other Epithelial Cysts


Cysts derived from the overlying epidermis, hair follicles, and apocrine glands include epidermoid cyst (Fig. 12.14), pilar or trichilemmal cyst, dermoid cyst (Fig. 12.15), and hidrocystoma [97]. Epidermoid cysts are often located in the labium majus and clitoris and occur as a result of trauma [98]. These cysts could develop many years after the initial injury [99, 100]. A rare presentation of clitoromegaly has been reported [101]. Less common entities include steatocystoma and cysts of anogenital mammary-like glands (previously reported as milk cysts of supernumerary mammary glands) [102]. Chuang et al. [103] described a case of multiple pigmented follicular cysts of the vulva, characterized by a stratified squamous epithelium with epidermoid keratinization containing multiple pigmented hair shafts and laminated keratin. Rare examples of apocrine cystadenoma and pigmented hidrocystoma derived from vulvar eccrine secretory coils have been reported by Glusac [104] and Kamishima [105], respectively.

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Fig. 12.14
Epidermoid cyst. The cyst wall is comprised of squamous epithelium containing a granular layer


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Fig. 12.15
Dermoid cyst. Hair follicles are seen inserting into the wall of the cyst


Miscellaneous Lesions



Mucinous Metaplasia of the Vulva


First reported by Coghill et al. [106], mucinous metaplasia is an extremely rare condition occurring in conjunction with an inflammatory process, strongly suggesting that it represents a secondary metaplastic phenomenon. There are distinctive clinical features. In the reported cases, mucinous metaplasia was found in females 60 years old and older in association with Zoon vulvitis and lichen sclerosus [106108].


Histologic Features


Columnar mucinous cells focally replacing the stratified squamous epithelium are present accompanied by features of Zoon vulvitis and lichen sclerosus [107, 108] (Fig. 12.16). The mucinous cells are decorated by mucin stains (e.g., Alcian blue) and periodic acid-Schiff with diastase digestion and are immunoreactive for CK7, CEA, EMA, estrogen receptors, and CAM5.2 [109].

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Fig. 12.16
Mucinous metaplasia. Columnar mucinous cells are seen instead of squamous epithelium (Courtesy of Dr. Maria Teresa Fernandez Figueras, Department of Anatomic Pathology, Hospital Universitari Germans Trias i Pujol, Barcelona, Spain)

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Nov 11, 2017 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Cysts, Glandular Lesions, and Others
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