Bullous Pilomatricoma of the Neck With Lymphatic Involvement: A Case Report.

Pilomatricoma is a benign adnexal neoplasm derived from hair matrix cells, most frequently occurring in children and young adults. Although it typically presents as a firm, well-circumscribed dermal nodule, several uncommon clinical variants have been described. Among these, the bullous (lymphangiectatic) variant is particularly rare and may clinically mimic cystic or vascular lesions, creating diagnostic difficulty. We report the case of a 19-year-old male who presented with a rapidly enlarging, translucent, bullous lesion in the posterior cervical region. Physical examination revealed a biphasic lesion consisting of a soft, fluctuant superficial component overlying a firm, mobile nodule, with positive transillumination. Ultrasonography demonstrated a well-defined subcutaneous mass measuring approximately 2.0 cm in depth, with mixed echogenicity and internal calcifications, without evidence of vascular flow. Complete surgical excision was performed. Histopathologic examination confirmed the diagnosis of bullous pilomatricoma, showing characteristic basaloid cells transitioning into ghost cells, dystrophic calcification, marked dermal lymphangiectasia, and foreign-body granulomatous reaction. Notably, pilomatricoma debris associated with granulomatous inflammation was identified within adjacent lymph node tissue, representing an exceedingly rare and previously unreported finding. Surgical margins were free of tumor, and no recurrence was observed at six-month follow-up. This case broadens the recognized clinical and histopathologic spectrum of bullous pilomatricoma and highlights the importance of considering this entity in the differential diagnosis of cystic-appearing lesions of the head and neck. Complete surgical excision remains curative and is associated with an excellent prognosis.