Glomus tumor of uncertain malignant potential in the arm of an elderly female – Report of an unusual case

Malignant glomus tumors (GTs) are very rare, and diagnosis requires consideration of specific histologic criteria based on a combination of criteria such as size of the tumor, degree of nuclear atypia, and the level of mitotic activity. GTs that do not fulfill the histologic criteria for malignancy but show at least one feature other than nuclear atypia should be classified as GT of uncertain malignant potential (GTUMP). We report the case of a 65-year-old female with a slowly progressing soft-tissue swelling in the right lower arm near the elbow joint that was successfully treated through wide surgical excision and histologically diagnosed as a GTUMP. On follow-up after 3 months, there was no evidence of recurrence or metastasis. Malignant GTs and GTUMPs are rare, and the nomenclature and classification of these tumors is controversial. These findings and the difficulty of differential diagnosis in a continuum between benignity and malignancy prompted our report.