Trichoblastoma

 Can be multiple in some cases



• Rare recurrences and association with, or progression to, malignancy [basal cell carcinoma (BCC)]




Macroscopic




• Nodular lesion involving deep dermis and subcutis

• Large, typically > 1 cm in diameter


Microscopic




• Large, basaloid-appearing deep dermal-based nodule
image Composed of irregular lobules and nests of basaloid cells

image No epidermal connections

• Associated fibrotic stroma with increased numbers of fibroblasts

• Papillary mesenchymal bodies classically present, similar to TE

• Subtypes include trichogerminoma, rippled-pattern trichomatricoma, trichoblastic fibroma, and cutaneous lymphadenoma


Top Differential Diagnoses




• BCC
image Usually shows multiple attachments to epidermis, mucinous stroma, and mitotic figures (focal or absent in TB)

• Trichoepithelioma
image Smaller and more superficial than TB

• Sebaceoma

• Cylindroma

• Spiradenoma

image
Clinical Photograph of Trichoblastoma on Eyelid
Clinical photograph shows a nodular lesion on the eyelid image of a patient with a history of multiple trichoblastomas and trichoepitheliomas (TEs).


image
Scanning Magnification of Trichoblastoma
Scanning magnification of a trichoblastoma shows a nodular basaloid proliferation associated with a fibrotic stroma. Note the presence of scattered folliculocystic structures image.

image
High Magnification of Trichoblastoma
High magnification of a trichoblastoma shows a lobular basaloid proliferation associated with a cellular, fibrotic stroma image. Note the prominent stromal-stromal retraction artifact image.

image
Trichoblastoma With Focal Sebaceous Differentiation
Trichoblastoma can show sebaceous differentiation in some cases. Scattered clear cells with multivacuolated cytoplasm are identified image.


TERMINOLOGY


Abbreviations




• Trichoblastoma (TB)


Synonyms




• Giant trichoepithelioma (TE)

• Trichogerminoma

• Rippled-pattern TB (trichomatricoma)

• Trichoblastic fibroma

• Cutaneous lymphadenoma


Definitions




• Benign dermal-based adnexal tumor showing primitive follicular differentiation


CLINICAL ISSUES


Epidemiology




• Incidence
image Uncommon tumors

• Age
image Usually occur in adults


Site




• Head and neck area, especially scalp


Presentation




• Dermal nodule/mass lesion
image Usually single but may rarely be multiple

• Usually asymptomatic


Treatment




• Surgical approaches
image Complete excision is curative

image Should be recommended in cases of partial biopsy in order to exclude basal cell carcinoma (BCC)


Prognosis




• Excellent in most cases

• Rare recurrences and association with, or progression to, malignancy (BCC)


MACROSCOPIC


General Features




• Nodular lesion involving deep dermis and subcutis


Size




• Large, typically > 1 cm in diameter


MICROSCOPIC


Histologic Features




• Large, basaloid-appearing deep dermal-based nodule
image Usually symmetric and shows well-circumscribed borders

image Composed of irregular lobules and nests of basaloid cells

image No epidermal connections

image May extend into superficial subcutis

• Associated fibrotic stroma with increased numbers of fibroblasts
image Stromal amyloid may be present

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Apr 24, 2017 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Trichoblastoma
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