A Case of Endocrine Mucin-Producing Sweat Gland Carcinoma Which Recurred 8 Years After Excision, and Exhibited Infiltrative Growth Pattern Without Any Mucinous Carcinoma.

An octogenarian man developed a recurrent cheek lesion 8 years after surgical resection. Although the histopathological features resembled those of endocrine mucin-producing sweat gland carcinoma (EMPSGC), small tumor nests lacking mucinous carcinoma components infiltrated the surrounding adipose tissue and striated muscle. This infiltrative morphology is inconsistent with the pushing invasion described by the WHO classification. To our knowledge, this is the first report of EMPSGC demonstrating this distinct growth pattern, the clinical significance of which remains unclear.