Glomus Tumor - Malignant Glomus Tumors

Malignant Glomus Tumors

Malignant glomus tumors, histologically and/or clinically are exceedingly rare. Criteria for the diagnosis of malignancy in glomus tumors are:

1. Tumor size of more than 2 centimeters and subfascial or visceral location.
2. Atypical mitotic figures.
3. Marked nuclear atypia and any level of mitotic activity.

• • Pericytes of Zimmerman

Malignant glomus tumors have been subdivided into three categories based on their histologic appearance: locally infiltrative glomus tumors (LIGT), glomangiosarcomas arising in benign glomus tumors (GABG), and glomangiosarcomas arising de novo (GADN).

A few cases of malignant glomus tumors have been reported; however, they are usually only locally invasive, and metastases are exceedingly rare. Brathwaite et al in 1996 reported widespread metastases of a malignant glomus tumor involving the skin, lungs, jejunum, liver, spleen, and lymph nodes. Another report of a malignant glomus tumor with metastases is that of Watanabe et al., who reported a cutaneous malignant glomus tumor with widespread metastases. A few other cases of malignant glomus tumors have been reported in the literature usually occur in the older age group, and have been described at several locations, primarily the soft tissues and gastrointestinal tracts.

Recently, Lamba G et al reported the first case of malignant glomus tumor arising from the kidneys.