Figure 1. Right lower back lesion diagnosed as squamous cell carcinoma on previous shave biopsy with final excisional biopsy results of squamoid ductal eccrine carcinoma. DESCRIPTION An 89-year-old man presented with a rapidly progressing lesion of the right lower back initially diagnosed as squamous cell carcinoma (SCC). Excisional biopsy showed primary squamoid eccrine ductal carcinoma (SEDC) with indistinct borders involving the deep margin. Further excision with 1-cm margins demonstrated perineural invasion. Oncology was consulted and recommended observation.