Solitary mastocytoma with associated pseudocarcinomatous hyperplasia

Large Congenital Cutaneous Mastocytoma Presenting With Recurrent Persistent Blistering: A Case Report

Congenital cutaneous mastocytoma is an uncommon disorder characterized by abnormal proliferation of mast cells. It typically presents as a single, small, yellowish-brown plaque, and its diagnosis is generally facilitated by distinctive clinical features, including a positive Darrier's sign. This report presents a case of an unusually large, solitary congenital mastocytoma encompassing nearly the entire circumference of the calf, observed in a newborn boy of Bangladeshi origin. Measuring 13x6 cm, the lesion formed large bullae and subsequent erosions. The perplexing clinical appearance prompted a skin biopsy, revealing monomorphic CD117 (c-KIT) positive infiltration without significant cell pleomorphism, confirming the diagnosis of cutaneous mastocytoma. The patient underwent management with potent and very potent topical steroids, oral antihistamines, and non-adhesive dressings, remaining under long-term follow-up with secondary care dermatology. In reporting this case, our objective is to augment the existing scientific literature by providing additional evidence that cutaneous mastocytomas can display a spectrum of clinical presentations, as illustrated in this case.

Verrucous hemangioma with pseudoepitheliomatous epidermal hyperplasia in an adult horse

Verrucous hemangiomas are a rare specific variant of equine skin tumors not well described in the literature. An 8-year-old gelding presented a unilateral lesion on the pastern. Macroscopically, the mass showed a warty and verrucous surface with focal ulcerations. The histology showed a dermal proliferation of endothelial-layered capillaries and venules separated by a delicate stroma of scant fibroblasts and collagen deposition, with pseudoepitheliomatous hyperplasia (exuberant reactive irregular epithelial hyperplasia with tongue-like projections extending into the dermis, mimicking downgrowth of squamous cell carcinoma) and orthokeratotic hyperkeratosis of the overlying epidermis. The immunohistochemical study confirmed the endothelial origin of the tumor, and a final diagnosis of verrucous hemangioma with pseudoepitheliomatous hyperplasia was confirmed. To the knowledge of the authors, this is the first detailed description of this entity in adult horses. Moreover, the clinical progression and epidermal changes have not been previously reported, emphasizing the importance of a pathological study of any epithelial preneoplastic lesion to rule out an underlying dermal neoplasia.