Basosquamous carcinoma (BSC) is a rare skin cancer that comprises less than 2% of nonmelanoma skin malignancies and presents frequently in patients aged 70 and older. Risk factors include ultraviolet (UV) exposure, tobacco use, xeroderma pigmentosum, immunosuppression, and Fitzpatrick skin types I-II. BSC has histopathologic features of squamous cell carcinoma (SCC) and basal cell carcinoma (BCC). Although its pathogenesis is not fully understood, recent literature suggests that BSC is a type of BCC that has genetically undergone partial squamatization. Compared to SCCs and BCCs, BSCs are more aggressive and associated with more significant rates of recurrence (up to 45%) and metastasis (approximately 5%-10%), with the most common sites being lymph nodes and lungs.
Codes
ICD10CM: C44.90 – Unspecified malignant neoplasm of skin, unspecified
SNOMEDCT: 254702000 – Basosquamous carcinoma of skin
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Differential Diagnosis & Pitfalls
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