A fifty-year-old male presented with a painless tumor mass of the forearm. The mass was surgically removed.

On macroscopic examination, there was a well-circumscribed nodule, 18-mm in diameter, with a reddish cut surface.

Histopathologic examination revealed regular vascular cavities surrounded by clusters of small round cells with ovoid nuclei and fine chromatin (Fig. 1 and 2). Immunohistochemical staining showed positivity of small round cells to anti-smooth muscle antibodies and negativity to anti-CD34 and anti-HMB45 antibodies (Fig. 3a – 3c). The diagnosis of glomangioma was retained based on these morphological and immunohistochemical findings.

	Figure 1: A proliferation with a marked vascular component surrounded by clusters of small round cells with ill-defined borders (H&E, 2x).
	Figure 2: Tumor cells with regular, rounded nuclei with homogenous chromatin and amphophilic cytoplasm (H&E, 40x).
	Figure 3: On immunohistochemical staining, the tumor cells showed positivity to a) the anti-smooth muscle actin antibody and negativity to b) anti-CD34 and c) anti-HMB45 antibodies.

Glomangioma is a variant of the glomus tumor. The latter is a mesenchymal proliferation that arises from the perivascular glomus body [1,2]. It presents typically as a swollen blue mass most commonly on the upper extremities with a predilection to the subungual area in the fingers. The forearm is an unusual site, and having a prominent vascular component is also infrequent [1,2]. They are, for the most part, benign. However, malignant variants do exist [3].

Consent

The examination of the patient was conducted according to the principles of the Declaration of Helsinki.

The authors certify that they have obtained all appropriate patient consent forms, in which the patients gave their consent for images and other clinical information to be included in the journal. The patients understand that their names and initials will not be published and due effort will be made to conceal their identity, but that anonymity cannot be guaranteed.

REFERENCES

1.  Gupta M, Sharma V, Mahajan VK, Singh R. Subungual glomus tumor:An uncommon cause of median canaliform nail-dystrophy of Heller. Our Dermatol Online. 2014;5:62-4.

2.  Awal G, Kaur N. Unusual presentation of a rare skin tumor:Glomangioma. Our Dermatol Online. 2024;15:206-7.

3.  Kawaguchi K, Endo M, Fukushima S, Hirose T, Nabeshima A, Fujiwara T, et al. Metastatic malignant glomus tumor resistant to pazopanib, a multikinase inhibitor:A case report and review of literature. JOS Case Rep. 2024;3:101-4.