PATH QUIZ CASE 5 -Case history and images:

Dermatopathology Case No 26 (Images)

The glomus tumour is a distinctive neoplasm which arises from modified smooth muscle cells of the normal glomus body.

[The glomus body is a specialized form of arteriovenous anastomosis  which is involved in temperature regulation. There is a central coiled canal known as Suquet-Hoyer canal which is lined by plump endothelial cells. This is surrounded by longitudinal and circular muscle fibres containing rounded epithelial appearing glomus cells. ]

Site:   Glomus tumours are commonly located in the subungual region of finger. Other sites include palm, wrist, forearm, foot and tip of the spine.

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.

Glomus tumour proper (solid glomus tumour)-  

Solitary painful lesion.

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:

             
Glomangioma-    

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.

Glomangiomyoma-    

Overall features are similar to glomus tumour and glomangioma.
There is gradual transition from round glomus cells to elongated  smooth muscle cells. These features are more obvious near large blood vessels.

 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

Glomangiosarcoma-  Patient with glomangiosarcoma usually developed widespread metastases.
Microscopic features:   Histologically, the features are those of benign glomus tumour with sarcomatous areas consisting of short spindle cells with hyperchromatic nucleus (round cell or leiomyosarcomatous appearance) and prominent mitotic figures.

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.

Glomus tumour of uncertain malignant potential:   Tumours that lack criteria for malignant glomus tumour or symplastic glomus tumour but have high mitotic activity and superficial location only or large size only or deep location only.

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.

Differential diagnosis:  Glomuvenous malformation (glomangioma) and venous malformation (Glomuvenous malformation (glomangioma) and venous malformation: distinct clinicopathologic and genetic entities. Arch Dermatol. 2004;140(8):971-6.)

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 ; Image Link2 ; Image Link3 ; Image Link4.

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.