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 EyelidClinical 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 TrichoblastomaScanning 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 TrichoblastomaHigh 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 DifferentiationTrichoblastoma 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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