Diagnosis-Malignant Glomus Tumor (Glomangiosarcoma)

Case Study

This is a 47 year old man who presents with a scaly nodule on the shoulder.

Diagnosis-Malignant Glomus Tumor (Glomangiosarcoma)

This is an extremely rare soft tissue sarcoma. About half of reported cases arise in a pre-existing glomus tumor, although this is not necessary for a diagnosis. The tumor is defined by the following:

Size>2 cm and deeply located
Marked nuclear atypia and elevated mitotic rates (>5 mitoses/50 high-power fields) OR
Display atypical mitotic figures

As in all glomus tumors, including this case, the tumor cells will stain strongly positive for smooth muscle actin. The prognosis is guarded with 38% of reported cases, that meet the above defined critera, developing metastases.

Addendum: Less than one week after this case was received, a second malignant glomus tumor on a different patient was also reviewed in consultation.

References:

The Doctor's Doctor-Glomus Tumors

Am J Surg Pathol 2001;25:1

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