Sporadic generalized basaloid follicular hamartoma presenting as itchy comedonal papules in an elderly male

Dear Editor,

Basaloid follicular hamartoma (BFH) is a rare benign hair follicular neoplasm with various presentations as papules/plaques, solitary/multiple, localized/generalized, and hereditary/acquired. It can appear on the head, neck, trunk, and arms. Herein, we report an elderly man with sporadic generalized BFH manifesting as itchy comedonal papules.

An 83-year-old male patient presented with the chief complaint of multiple itchy brown papules, most with single and some with double open comedones on face, scalp, neck, and upper trunk of 4-month duration [Figure 1]. He had no history of medical illnesses or smoking. With differential diagnoses (DDs) of senile comedones and follicular mycosis fungoides (MF), a biopsy of a papule showing double comedones was sent for histopathology, which showed basaloid cells in nests and anastomosing strands arising from the pilosebaceous unit of 2 hair follicles and a few horn cysts [Figures 2 and 3]. This was consistent with BFH. There was no other physical abnormality detected. He is currently being treated symptomatically with tablet hydroxyzine and is under observation.

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Figure 1:

Brown papules mostly with central comedones on the patient’s chest.

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Figure 2:

Histopathology showing anastamosing strands and nests of basaloid cells arising from pilosebaceous unit (black circle) (Hematoxylin and eosin, 40x).

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Figure 3:

Tumour cells with scant eosinophilic cytoplasm and uniform bland looking nuclei (red circle) and surrounding loose fibrous stroma (Hematoxylin and eosin, 400x).

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Generalized BFH has the following forms, namely (1) sporadic, (2) acquired, (3) familial (autosomal dominant), and (4) congenital forms.^[1-4] Some of its associations include autoimmune diseases such as systemic lupus erythematosus, myasthenia gravis (acquired); palmar pits, hypotrichosis, hypohidrosis (familial); alopecia; and cystic fibrosis (congenital). Because of the late onset, lack of similar family history, and other associated diseases, our patient was diagnosed as sporadic generalized BFH.

The unusualness in our case was the presence of comedones within these papules. Biopsy helped in clinching the right diagnosis. Senile comedones show dilated and plugged follicular infundibulum with or without nodules of elastotic material due to actinic damage. Follicular MF can present with comedo-like lesions with histopathology showing atypical lymphocytes selectively infiltrating follicular epithelium. One case report of hereditary generalized BFH syndrome with milia and comedone-like lesions is reported so far.^[1] Although in general, BFH is asymptomatic, our patient had pruritus confined to the lesions.

Similar to nevoid basal cell carcinoma (BCC), BFH formation has been linked to patched-1 gene mutation. Though mostly benign, monitoring of BFH is important due to the risk of malignant transformation. Basaloid follicular proliferation can also be seen overlying benign tumors like dermatofibroma, but lacks keratin cysts and distorted hair follicles, unlike in BFH. The most important DD is multiple infundibulocystic BCC (IBCC). Common histopathological features include the presence of basaloid cells in cords and strands surrounded by a loose, fibrous stroma and horn cysts.^[5] But unlike BFH, IBCC is not folliculocentric and lacks pilosebaceous structures due to their destruction by the malignant cells. Prominence of mitosis, epidermal ulceration, and deeper infiltration point to a diagnosis of IBCC.^[2] These were absent in our patient who had stable folliculocentric lesions clinically and histologically. IHC can help in differentiating both but it could not be done due to financial constraints.

To conclude, BFH should be considered as a differential for itchy comedonal papules in elderly individuals and should be confirmed by biopsy.