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February
2009
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The glomus tumour is a
distinctive neoplasm which arises from modified smooth muscle cells of the
normal glomus body. Rarely, the tumour may occur in the gastrointestinal tract (stomach, small intestine, colon), trachea, lungs, mesentery, bone, vagina and the cervix. A glomus tumour is rare in the sinonasal region. Almost all cases of sinonasal glomus tumor are benign and are usually cured by complete excision. Cutaneous lesion usually occurs in adults (20- 40 years) and presents as small blue red nodule in the deep dermis or subcutis. Intravascular spread of
the glomus tumour is rare and has been described in the stomach and
subcutaneous tissue. Most frequent location is the forearm. The
pathologist must be aware of this variant of glomus tumour to avoid
misdiagnosis and unnecessary additional treatments. Microscopic features: Histologically, this is a well circumscribed lesion characterized by solid aggregates of glomus cells around small capillary sized vessels in a myxoid or hyalinized stroma. The glomus cell is round, regular shaped with a sharply punched out rounded nucleus. Rare variants: I. Epithelioid: Unlike conventional glomus tumors, which consist of small polygonal cells with dark round nuclei and scanty cytoplasm, the epithelioid lesions are composed of large polygonal to spindle-shaped cells with abundant eosinophilic cytoplasm and large, irregularly shaped nuclei. The cells have both epithelioid and myoid qualities. Differential diagnosis: Spindle-cell lesions, such as schwannoma, leiomyoma, hemangiopericytoma.
II. Oncocytic: Three different clinical variants of glomangioma have been recognized: solitary, multiple, and nodular, or plaquelike. Glomangiomas are usually painless. These are mostly noted in adolescence and is less common than glomus tumour proper. Microscopic features:
Histologically, these
are poorly circumscribed, unencapsulated lesions characterized by
prominent ectatic vessels and less conspicuous glomus cells. Secondary
thrombosis and phlebolith formation may occur. The features resemble those
of cavernous hemangioma.
I Classification of unusual glomus tumours: (Gould et al) 1. Locally infiltrative glomus tumour;
2. Cytologically malignant tumour arising and merging with typical glomus
tumour (glomangiosarcoma arising in a benign glomus tumour). 3.
De novo glomagiosarcoma II Classification of atypical glomus tumours : (Folpe et al.) 1. Malignant ; 2. Symplastic ; 3. Glomus tumors of uncertain malignant potential, and 4. Glomangiomatosis Atypical glomus tumour: Glomus tumours display unusual features, such as large size, deep location, infiltrative growth, mitotic activity, nuclear pleomorphism, and necrosis. Atypical features are usually observed centrally with a rim of benign-appearing glomus tumour. Malignant glomus tumour: Tumour with a deep location and a size of more than 2 cm, or atypical mitotic figures, or moderate to high nuclear grade and 5 mitotic figures or more/50 HPF. High nuclear grade alone, infiltrative growth, and vascular space involvement are not associated with metastasis.
Symplastic:High nuclear grade in the absence other malignant features.IMAGE Glomangiomatosis: Tumours with histologic features of diffuse angiomatosis and excess glomus cells. Immunohistochemistry: The tumour cells reveal
immunopositivity for vimentin, smooth muscle actin and muscle specific
actin in the cytoplasm. The cells do not stain with endothelial markers.
Desmin is occasionally only focally positive. Adnexal tumour- eccrine spiradenoma (two population of cells and focal ductal differentiation); Hemangiopericytoma (spindle shaped cells and branching staghorn vessels); Intradermal naevus with pseudovascular spaces (focal nesting, S100 positive and evidence of maturation) ; Rhabdomyosarcoma ; Ewing's sarcoma/PNET; Nodular hidradenoma; Leiomyosarcoma with epithelioid change Glomus
Tumour of the Lung: click here
Microscopic features of Gastric Glomus
Tumour:
Image
Link1 Glomus tumours have been reported in the stomach and occasionally in the intestines. Gastrointestinal glomus tumours occur most commonly in older women. Gastric glomus tumours usually occur in the gastric antrum of adults. It is the second commonest site after the skin. These are mostly benign lesions. Malignant tumours have been reported with metastases to the liver, lymph nodes, and peritoneum. The gastric tumours typically presents with gastrointestinal bleeding. The mucosa overlying the tumour is often ulcerated. In some cases the tumours are incidental findings during clinical evaluation or abdominal operation. The average size of the intramural nodules are 2 to 2.5 cm and are mostly located in the muscularis propria. Pseudocapsule may form around the lesion. Immunohistochemistry: The lack of CD117 positivity has been described as a feature of glomus tumour of gastrointestinal origin, and this helps to distinguish glomus tumour from gastrointestinal stromal tumours. Leukocyte common antigen and neuroendocrine markers, such as synaptophysin and chromogranin, are negative. Smooth muscle actin and muscle-specific antigen, are positive Differential diagnosis: Epithelioid stromal tumour ; Carcinoid ; Malignant lymphoma.
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