Malignant Cutaneous Adnexal Tumors and Role of SLNB

Malignant cutaneous adnexal tumors (MCATs) are rare and their natural history is poorly understood. Available literature indicates aggressive behavior with a significant risk of metastasis.

Retrospective review of our institutional surgical oncology databases was performed for patients diagnosed with MCATs (2001-2020). We hypothesized that 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.

We identified 41 patients diagnosed with MCATs (median age 59 years, 68% were men). Most patients had long-standing cutaneous lesions (median 24 months) and no palpable adenopathy. Most patients had stage I or II disease (98%). Primary tumors were treated with wide local excision (n = 28 [68%]), Mohs surgery (n = 5 [12%]), or amputation (n = 8 [19%]). Of 25 patients who underwent SLNB (61%), 1 had lymphatic metastasis. These include apocrine carcinoma (1 of 3), digital papillary adenocarcinoma (0 of 8), porocarcinoma (0 of 4), and additional MCAT sub-types (0 of 10). Three patients (7%) had disease recurrence at a median interval of 3.6 years (interquartile range 1.5 to 4.4 years). Five patients (12%) died at a median interval of 7 years (interquartile range 6.7 to 9.2 years), but only 1 patient was known to have succumbed to MCAT. Overall 5-year survival rate was 96% (95% CI, 75% to 99%).

Despite the historical impression that MCATs have a high metastatic potential, most patients have low recurrence rates and excellent 5-year survival rates. Lymphatic disease identified after SLNB in early-stage tumors is rare and the value of this staging procedure in MCAT remains unclear.