Glomus tumours in the skin and subcutis of three horses

Abstract

Three horses presented with variably painful, nonulcerated masses of the head or neck that were diagnosed as glomus tumours. Grossly, they were fleshy, pink to tan masses ranging from 0.4 to 9 cm in diameter, involving either the deep dermis and subcutis or the subcutis and underlying skeletal muscle. Microscopically, neoplastic epithelioid cells were arranged in sheets, cords and packets within lobules. The neoplastic cells frequently abutted and formed nodular bulges into large endothelium-lined vascular spaces, especially around the tumour periphery. Large nerve branches were associated with each tumour. As determined by immunohistochemistry, the neoplastic cells consistently expressed α-smooth muscle actin and vimentin, and some cells in two of the cases expressed desmin. A laminin- or collagen IV-positive basement membrane was demonstrated around individual tumour cells or small groups of cells in all three cases. Morphological features and immunohistochemistry supported the diagnosis of glomus tumour, most consistent with the solid type in humans. Applying a classification system used in humans, two of these tumours met criteria of malignancy (glomangiosarcomas). One horse was euthanized due to complications associated with recurrence and treatment-related necrosis and secondary infection.

What is your diagnosis? A dermal mass in a dog

“…A unique feature of this neoplasm is the entrapped vascular structures, identified both cytologically as capillaries and histologically as large clefts, as in this case . The fibrous capsule and embedded vessels and nerves were also frequently observed …”

“…Histologic descriptions of the neoplastic cells vary from round to polygonal, and acinar‐like structures or cords are often described . A unique feature of this neoplasm is the entrapped vascular structures, identified both cytologically as capillaries and histologically as large clefts, as in this case . The fibrous capsule and embedded vessels and nerves were also frequently observed …”

Dermatopathology – the link between ancillary techniques and clinical lesions

“…The use of antibodies in diagnostic pathology has become an indispensable technique that is routinely used by many diagnostic laboratories and pathologists . Pathologists often have to rely on the immunophenotype of a neoplastic cell population to identify its origin . However, antibodies are specific for an antigen in a specific species.…”

“…7 Pathologists often have to rely on the immunophenotype of a neoplastic cell population to identify its origin. [8][9][10] However, antibodies are specific for an antigen in a specific species. Prior to using an antibody in a different species, it has to be evaluated carefully for its potential for correct crossreactivity in this new species.…”

“…There are innumerous examples of the use of antibodies to immunophenotype neoplastic processes, including leukocytic tumours (Figure 1), cutaneous glomus tumours and amelanotic melanomas. [8][9][10]18,19 As intranuclear inclusion bodies are not always evident on H&E, identification of papilloma virus typically is dependent on using the cross-reactive anti-bovine papilloma virus (BPV)-2 antibody. 12 With acute and subacute distemper, canine distemper virus can be identified within keratinocytes of haired skin, footpads and nasal mucosa.…”