Primary glomangioma of the liver: a case report and review of the literature.

Glomangiomas are a subset of glomus tumors that have a rich vascular network. Although a majority of the glomus tumors occur in the skin of the hand, they have also been reported in the deep soft tissue, bone, lungs, and gastrointestinal tract, especially the stomach. To our knowledge, only one such case has previously been reported primarily occurring in the liver. We report a case of a glomangioma primarily arising in the liver of a 57-year-old man who presented with right flank pain of several months' duration. A 3.0-cm hepatic mass was excised and consisted of numerous, small-to-medium branched vessels with the stroma containing small, round, regular cells with sharply outlined round-to-oval nuclei. Immunostains showed the tumor cells to be diffusely positive for vimentin and smooth muscle actin and to be focally positive for calponin. Collagen IV stained the pericellular matrix. The immunostain for CD34 highlighted the vascular network as well as outlined the tumor cells in many areas. Coexpression of actin and CD34 in glomus tumors, although unusual, has recently been reported in the literature. Despite its bland histology, the large tumor size and deep visceral location were suggestive of aggressive behavior; thus, a close clinical follow-up was recommended. The patient had an unremarkable postoperative course and has no evidence of metastatic disease 12 months after the procedure. An accurate diagnosis and an understanding the biology of this rare disease, especially in an unusual location, are crucial to its management.