Abstract:

Basaloid follicular hamartoma (BFH) is a rare, benign neoplasm of the hair follicle. It presents as small, brown papules on the face, scalp and trunk and manifests as different clinical scenarios including solitary lesions or multiple lesions with a generalized or localized linear unilateral distribution. On the molecular level, changes in PTCH signaling pathway contributes to the pathogenesis. BHF can be part of several syndromes and be associated with alopecia, palmar pitting, hypohidrosis, hypotrichosis, myasthenia gravis, systemic lupus erythematosus and Cystic Fibrosis. Histologically hair follicles are associated with branching strands of undifferentiated basaloid cells in a fibrous stroma. The most important histologic differential diagnosis is basal cell carcinoma, in particular the infundibulocystic variant. We report a 15-year-old girl with unilateral asymptomatic, slow-growing skin lesions on the left side of her face and neck present since birth. The lesions are linearly distributed, multiple (5.0 cm collectively), variably- sized, somewhat confluent, brown papules of up to 8 mm size in the periauricular and postauricular regions, earlobe and neck, clinically favored to be epidermal nevi. There is no family or past medical history of similar lesions. Of five clinically described variants of BFH, our current case is best categorized as the linear unilateral form with distribution along Blaschko lines. Histologic examination demonstrated basaloid cells growing in anastomosing strands and cords and nodules within a loose, myxocollagenous stroma. Horn cysts and a few hair shafts were present. There was no direct connection of the epithelial cells with the epidermis, and papillary mesenchymal bodies were not seen.

Financial Disclosure:
No current or relevant financial relationships exist.

Menu

Sara Moradi, MD