Low-Grade Malignancy Glomus Tumor in a Setting of Multiple Glomus Tumors - Case Report.

Background: Glomus tumors are rare neoplasms accounting for less than 2% of all soft tissue tumors but multiple lesions may be seen in up to 10% of the patients. Solitary glomus tumor (GT) most frequently appears as small nodule in specific locations such as subungual region or deep dermis. However, rarely these entities have been observed in extracutaneous locations such as the gastrointestinal, cardiovascular, respiratory tracts, and other visceral organs. A small fraction of the GTs may present as tumors of uncertain malignant potential or as malignant glomus tumors.

Case Presentation: We report a patient with multiple glomus tumors on the time of diagnosis, which was histologically diagnosed as an atypical glomus tumor following resection of a tumor thrombus in the left renal vein, inferior vena cava trombus with intracardial extension, and mitral valve specimen. The intramuscular lesion from the thigh was diagnosed as a glomus tumor of uncertain malignant potential. Further examinations revealed multiple lesions trough her body: kidneys, breast, heart and subcutaneous tissue. The diagnosis of glomus tumor of uncertain malignant potential versus glomus tumor with low malignant potential could be quite challenging, and the clinical course may be as a determining factor for final diagnosis.

Conclusion: To our knowledge, this is the only known case of glomus tumor with multiple organ involvement and aggressive biological behavior at presentation.