Giant intravenous glomus tumor.

We report a painful intravenous glomus tumor located in the right forearm of a 79-year-old woman. The tumor originated from the wall of a vein, protruded into its lumen and was completely excised. The largest dimension of the tumor occluding the vein was 14 cm. Tumor cells were characterized immunohistochemically by the presence of vimentin, alpha-smooth-muscle actin, and collagen IV. Intravascular spread of the glomus tumor is rare and has been described in the stomach and subcutaneous tissue. An entirely intravenous glomus tumor has been reported only three times. However, a huge intravenous growth as in our case appears never to have been reported. A review of the intravascular cases showed that the average age of presentation is 61.5 years (range 40-79 years) and the most frequent location is the forearm. Despite this intravascular growth, there is no evidence of aggressive clinical behavior, recurrence or metastasis. The pathologist must be aware of this variant of glomus tumor to avoid misdiagnosis and unnecessary additional treatments.