LAUSR

BACKGROUND Malignant adnexal cutaneous tumors (MACT) are rare and their natural history is poorly understood. Available literature indicates aggressive behavior with a significant risk of metastasis. STUDY DESIGN Retrospective review of our institutional surgical oncology databases was performed for patients diagnosed with MACT (2001-2020). We hypothesized most patients have a low risk of lymph node involvement, recurrence, and death. Kaplan-Meier statistical analysis was used to assess risk of recurrence and 5-year survival. RESULTS We identified 41 patients diagnosed with MACT (median age 59, 68% male). Most patients had long-standing cutaneous lesions (median 24 months) and no palpable adenopathy. Most had stage I or II disease (98%). Primary tumors were treated with wide local excision (28, 68%), Mohs surgery (5, 12%), or amputation (8, 19%). Of 25 patients that underwent sentinel lymph node biopsy (61%), one had lymphatic metastasis. These include apocrine carcinoma (1/3), digital papillary adenocarcinoma (0/8), porocarcinoma (0/4), and additional MACT sub-types (0/10). Three patients (7%) had disease recurrence at a median interval of 3.6 years (IQR 1.5- 4.4). Five patients (12%) died at a median interval of 7 years (IQR 6.7- 9.2), but only one patient was known to succumb to MACT. The overall five-year survival was 96% (95% CI 75- 99). CONCLUSION Despite the historical impression that MACTs have a high metastatic potential, most patients have low recurrence rates and excellent 5-year survival. Lymphatic disease identified after SLNB in early stage tumors is rare and the value of this staging procedure in MACT remains unclear.