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Pathology of Basaloid Follicular Hamartoma

Dr Sampurna Roy MD        


Dermatopathology Quiz Case 132

Diagnosis : Basaloid Follicular Hamartoma




Basaloid follicular hamartoma (BFH) is a benign adnexal tumour characterized by superficial dermal proliferation of thin basaloid cords in a fibrous stroma.

These lesions are regarded as malformation of hair follicle.

Basaloid follicular hamartoma may be congenital or acquired.

The congenital form can be further divided into the generalized and unilateral type.

The acquired form may present as localized and solitary lesions.

Congenital, generalized Basaloid follicular hamartoma (BFH) is associated with systemic diseases such as alopecia, cystic fibrosis, hypohidrosis, and myasthenia gravis.

Sporadic cases present as unilateral or localized lesions.

These lesions are usually located on the scalp, face and rarely on the chest, back and extremities.

Clinically, basaloid follicular hamartoma presents as a brown or skin coloured papule or plaque.

BFH is linked to a mutation in the patched (PTCH) gene on chromosome band 9q23.


Microscopic features:

The tumour shows thick cords and thin strands of anastomosing basaloid proliferations that arise from hair follicles and are enclosed by loose fibrous stroma.



Immunohistochemistry: The lesion shows CD34-positive, mildly cellular myxoid stroma with many CK20-positive Merkel cells scattered within the basaloid cellular strands, which exhibited BCL-2 positivity only within the outermost cells bordering the stroma.

These immunohistochemical features are the opposite of those displayed by basal cell carcinomas, which require more aggressive surgical management.

Differential diagnosis :  Besides basal cell carcinomas, the differential diagnosis of basaloid follicular hamartoma includes, Tumour of the Follicular Infundibulum ; Poroma , and trabecular (Merkel cell) carcinoma.


Further reading:

Basaloid follicular hamartoma of the eyelid.

Basaloid follicular hamartoma: a case report and review of the literature.

A novel phenotype with features of basal cell nevus syndrome and basaloid follicular hamartoma syndrome.

Basaloid follicular hamartoma.

Segmentally arranged basaloid follicular hamartomas with osseous, dental and cerebral anomalies: a distinct syndrome.

Familial basaloid follicular hamartoma: a report of one family.

Bcl-2, CD34 and CD10 expression in basaloid follicular hamartoma, vellus hair hamartoma and neurofollicular hamartoma demonstrate full follicular differentiation.

Hereditary basaloid follicular hamartoma syndrome.

Basaloid follicular hamartoma.

Linear basaloid follicular hamartoma on the Blaschko's line of the face.

Treatment of diffuse basal cell carcinomas and basaloid follicular hamartomas in nevoid basal cell carcinoma syndrome by wide-area 5-aminolevulinic acid photodynamic therapy.

Basaloid follicular hamartoma with trichoblastomatous proliferations.

Basaloid follicular hamartoma with eruptive milia and hypohidrosis: is there a pathogenic relationship ?

Basaloid follicular hamartomas associated with autoimmune disease: a possible role for retinoids in therapy.

Basal cell carcinomas in association with basaloid follicular hamartoma.

Familial basaloid follicular hamartoma: lesional characterization and review of the literature.




Dr Sampurna Roy  MD

Consultant  Histopathologist (Kolkata - India)







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