Sporotrichoid Keratoacanthomas: Case Report and Review of Neoplasms Presenting in a Sporotrichoid Pattern

Sporotrichosis is a fungal infection known for its distinct pattern of infectious skin nodules. Several conditions can present with lesions that appear in a sporotrichoid pattern. An 82-year-old man that presented with three cutaneous nodules on his right leg in a sporotrichoid manner is described; biopsy of each lesion revealed a keratoacanthoma. In addition to keratoacanthomas, other neoplasms—albeit rarely—may be observed to occur in a sporotrichoid manner. These included squamous cell carcinoma (three patients), lymphoma (two patients), and one patient with each of the following: epithelioid sarcoma, Langerhans cell histiocytosis, melanoma, and peripheral nerve sheath tumor. The 10 patients whose cancer had cutaneous lesions that presented in a sporotrichoid distribution ranged from 28 to 83 years old. The tumors equally appeared on either the upper extremity (five patients) or the lower extremity (five patients). Treatments included systemic chemotherapy, surgical intervention, and radiation. Three of the patients died secondary to their tumors. In conclusion, various infections and some miscellaneous disorders can present in a sporotrichoid pattern. Keratoacanthomas can be added to the list of cancers (which include squamous cell carcinoma, lymphoma, epithelioid sarcoma, Langerhans cell histiocytosis, melanoma, and peripheral nerve sheath tumor) whose skin lesions have appeared in a sporotrichoid distribution. When cutaneous lesions appear in a sporotrichoid manner, biopsy of the tissue—for not only microscopic examination but also bacterial, fungal, and mycobacterial cultures—should be considered.