Bullous pilomatricoma: a rarely reported variant of pilomatricoma

Abstract

Pilomatricomas are cutaneous adnexal tumors with matrical differentiation. We report and describe a rare variant called bullous pilomatricoma. Case synopsisA 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 previous 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.

Pseudobullous pilomatricoma: A rare variant of pilomatricoma

“… 4 Although PM can be associated with genetic disorders, such as myotonic dystrophy and Turner's syndrome, pseudobullous PM is unrelated to genetic disorders as per the literature review by Chen et al. 5 On histological examination, pseudobullous PM often presents with tumour nests in the deep dermis composed of basophilic and shadow cells (ghost cells), numerous dilated lymphatic vessels, and lymphoedema in the superficial dermis. The usual differential diagnosis for such lesions includes lymphangioma, malignant tumours, and bullous morphea.…”

“…3 This particular type of PM most commonly affects females aged 10-20 years, in the arm and shoulder. 4 Although PM can be associated with genetic disorders, such as myotonic dystrophy and Turner's syndrome, pseudobullous PM is unrelated to genetic disorders as per the literature review by Chen et al 5 On histological examination, pseudobullous PM often presents with tumour nests in the deep dermis composed of basophilic and shadow cells (ghost cells), numerous dilated lymphatic vessels, and lymphoedema in the superficial dermis. The usual differential diagnosis for such lesions includes lymphangioma, malignant tumours, and bullous morphea.…”

“…The usual differential diagnosis for such lesions includes lymphangioma, malignant tumours, and bullous morphea. 4 , 5 …”

“…On histological examination, pseudobullous PM often presents with tumour nests in the deep dermis composed of basophilic and shadow cells (ghost cells), numerous dilated lymphatic vessels, and lymphoedema in the superficial dermis. The usual differential diagnosis for such lesions includes lymphangioma, malignant tumours, and bullous morphea 4,5 …”

“…The usual differential diagnosis for such lesions includes lymphangioma, malignant tumours, and bullous morphea. 4,5 Presently, the etiopathogenesis of pseudobullous PM is not clearly understood. Some reports suggest that the elastinolytic enzymes produced by tumour cells and lytic products may cause the decline of elastic fibres and demolition and dilation of the lymphatic vessels, causing lymph fluid accumulation in the dermis, and consequently forming a bullous appearance.…”