Concurrent Nasal Sebaceous Carcinoma and Right-Hand Squamous Cell Carcinoma: A Case Report and Literature Review.

Cutaneous squamous cell carcinoma (cSCC) is the second most common nonmelanoma skin cancer with an increasing incidence. Sebaceous carcinoma (SC) is a rare, highly aggressive malignant tumor of cutaneous appendage origin, mainly occurring in the head and neck region (most commonly in the ocular area), and extremely rare in the nasal region. A literature review showed that only 3 cases of collision tumors composed of SC and squamous cell carcinoma (SCC) have been reported previously, and there is no report of concurrent SC and cSCC in different sites of the same patient. Combined with a literature review, this paper reports an 84-year-old female patient with progressive ulcerative skin lesions on the right hand and nose for 5 years. Initial biopsy suggested cSCC of the hand and sebaceous adenoma of the nose. After surgical excision, postoperative pathology and immunohistochemistry confirmed well-differentiated cSCC of the right hand and SC of the nose. Oncology consultation recommended adjuvant radiotherapy for nasal SC after surgery, which was refused by the patient's family due to her advanced age; no recurrence or metastasis was observed in either of the two lesions during the 5-month postoperative follow-up period. By analyzing this rare case of multicentric primary cutaneous malignant tumors combined with relevant literature, we emphasize that elderly patients with long-standing chronic skin lesions require comprehensive screening to avoid missed diagnosis. Accurate diagnosis relies on pathology and immunohistochemistry, surgical resection is the main treatment, and long-term follow-up is crucial. This case enriches the clinical data on concurrent SC and cSCC, providing references for their diagnosis and treatment.