Gastrointestinal glomus tumour

Epidemiology

Glomus tumour most commonly occurs in peripheral soft tissues. Approximately 100 glomus tumours of the gastrointestinal tract have been described, most predating immunohistochemistry. There is a marked female predominance (~3:1). Most occur in the stomach, usually in the antrum, with a very few intestinal cases.

Clinical features

Patients may present with anaemia, melena, haematemesis and ulcer-like pain.

Macroscopic appearances

These tumours are usually circumscribed, round or oval and are intramural. They may appear multinodular. On sectioning, they vary from soft to rubbery and are variably white, pink, red or brown. Calcification may be apparent.

Histopathology

Multiple cellular nodules are separated by bands of gastric smooth muscle. There may be a fibrous capsule. Dilated veins are commonly apparent, with tumour cells infiltrating the veins. There may be pericytomatous dilated capillaries. The stroma may be hyalinised. There are infiltrating variants with multiple cellular nodules within a desmoplastic stroma.

The tumour cells have sharply demarcated cell membranes and central round uniform nuclei with fine chromatin and inconspicuous nucleoli. Focally, the cytoplasm may be oncocytic or clear and the cells may be spindled. Haemorrhage and cystic change are common, but not coagulative necrosis. Calcification or osseous metaplasia are common. Mitotic counts of up to 4/50 HPF are seen, but not atypical mitoses.

Immunohistochemistry, with peripheral glomus tumour and epithelioid GIST for comparison. GIST are about 100 times more common.

	GI glomus tumour	peripheral glomus tumour	Gastric epithelioid GIST
smooth muscle actin	23/23	31/34	3/13
calponin	11/11	25/30	2/13
h-caldesmon	7/11	27/31	10/13
desmin	0/17	0/34	0/13
vimentin	17/17	34/34	13/13
collagen type IV	15/16	31/34	4/11
laminin	18/20	30/33	2/11
CD34	4/20	18/34	9/13
CD117	0/18	0/30	13/13
S-100	0/20	0/34	0/13
Cytokeratin 18	0/14	0/34	2/11
chromogranin	0/13	0/34	0/11
synaptophysin	3/17	0/34	0/11
CD20	0/17	0/34	0/11
CD45 (LCA)	0/17	0/34	0/11

Differential diagnosis

GIST is positive for CD117 as well as usually for CD34. Positivity for SMA is less common. Prominent basement membrane and dilated veins are lacking.
carcinoid: is synaptophysin-positive as well as chromogranin-negative and is positive for cytokeratins. It is typically mucosal or submucosal.
paraganglioma more commonly occurs in the retroperitoneum, mesentery and omentum. It is strongly positive for chromogranin as well as synaptophysin. S-100 positive sustentacular cells are present.
haemangiopericytoma is restricted to the mesentery and retroperitoneum.
solitary fibrous tumour is restricted to the mesentery and retroperitoneum.
vascular leiomyoma is positive for both smooth muscle actin and desmin.
lymphoma, particularly MALToma is positive for CD45 and CD20.
Infiltrating desmoplastic variants may resemble desmoplastic small round cell tumour.

Prognosis

A minority (1 of 151) of tumours metastasis and cause death. The rate of malignant behavior is lower than for glomus tumours at deep soft tissue sites.

References

1Miettinen, M., Paal, E., Lasota, J., Sobin, L. H. Gastrointestinal glomus tumors: a clinicopathologic, immunohistochemical, and molecular genetic study of 32 cases. Am J Surg Pathol 2002;26:301-311

This page last revised 1.5.2002.