Pilomatricomas are cutaneous adnexal tumors with matrical differentiation. We report and describe a rare variant called bullous pilomatricoma. Case synopsis A female in her 20s presented for evaluation and treatment of an enlarging blister on her right arm of nine months duration. She reported that the area first appeared similar to a bruise and subsequently enlarged to form a blister-like lesion. The patient could not recall any inciting trauma and denied pain or tenderness to palpation. No

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... vious treatment was attempted. Her past medical history, past surgical history, family history, and social history were unremarkable. On physical examination, there was a 3.5 x 3cm pink bulla containing palpable firm nodules on the right upper arm (Figure 1 ). It extended 1.5cm from the epidermal surface. There was no background erythema. Upon palpation, a sharp drop-off was noted between lesional and normal skin. Excisional biopsy was performed. The incised specimen revealed gelatinous material containing several calcified nodules (Figure 2 ). Histopathology revealed dilated, thin-walled vascular structures within the papillary dermis ( Figure 3 ). Deeper in the dermis there was a multilobulated tumor, surrounded by a fibrous pseudocapsule of compressed connective tissue elements. An admixture of basaloid and ghost cells were seen within the tumor and focal calcifications were present (Figure 4) . The final diagnosis was determined to be a bullous pilomatricoma.