Extradigital glomangiomyoma of the forearm mimicking peripheral nerve sheath tumour and thrombosed varicose vein

Abstract

Extradigital glomus tumour is uncommon, little-known outside of its subungual location, and may present without its classic triad of tenderness, cold sensitivity and paroxysmal pain. Imaging is non-specific and diagnosis is often delayed, sometimes for years, leading to unnecessary morbidity. Surgical excision is the treatment of choice, although technique depends on case specifics. Histological subtypes depend on the relative prominence of glomus cells, vascular structures and smooth muscle. The vast majority of glomus tumours are benign. We highlight the importance of considering extradigital glomus tumours when generating differential diagnoses of an atypical painful lesion in a variety of clinical specialties.

Keywords: musculoskeletal and joint disorders; orthopaedic and trauma surgery; plastic and reconstructive surgery.

Figure 1

Coronal T2 fat saturated MRI image of the lesion showing high signal intensity.

Figure 2

Coronal T1 MRI image of the lesion showing isosignal intensity.

Figure 3

Ultrasound image of the lesion (red arrow) demonstrating brisk Doppler signal and its location adjacent to the basilic vein (blue arrow).

Figure 4

Intraoperative photograph showing the lesion adherent to the basilic vein.

Figure 5

Intraoperative photograph showing the unaffected dorsal ulnar nerve on deeper dissection after lesion removal.

Figure 6

Histological examination at ×2 objective (H&E stain) showing a vein (bottom right) to which the glomangiomyoma is attached. The tumour contains an organoid mixture of thick-walled, muscular blood vessels, solid sheets of small, uniform glomus cells and irregular, thin-walled vascular channels. There are interspersed areas of smooth muscle which merge focally with the glomus cells.

Figure 7

Histological examination at ×4 objective (H&E stain) showing glomus cells (dark nuclei), including a sheet of epithelioid glomus cells with more abundant, paler cytoplasm (red star), with dilated vascular channels lined by smooth muscle cells (blue star).

Figure 8

Histological examination at ×40 objective (H&E stain) showing glomus cells (red arrow) merging with smooth muscle cells (blue arrow).