Case 1: Vessels are surrounded by an infiltrate of glomus cells, which are uniform and round.
The glomus tumor cells will abut the endothelium of the lesional vessels, which do not have an elastic lamina.
Glomangioma is a variant of the glomus tumor, consisting of a large vessels with cavernous and dilated lumens. The vessel walls are often hyalinized as seen in this image.
Another image of a glomangioma, with a large hyalinized vessel surrounding by glomus cells. Note that the glomus cells have a trabeculated arrangement in the upper left.
Glomus tumor cells are monomorphic, with round centrally located nuclei and pale pink cytoplasm. Mitoses is normal, but rarely seen.
Case 2: A well-circumscribed nodule is seen in the subcutis. Glomus tumors are usually located in the dermis or subcutis.
A closer look at the nodule with prominent vasculature, surrounded by monotonous cells. Glomangiomas (a variant) are even more vascular.
The glomus cells have small nuclei, around 10 microns (a RBC is about 9 microns).
A glomus body is a richly innervated structure located in the fingertips and palms involved in thermoregulation. It consists of an arterial and venous portion, and the arterial portion is called the Sucquet-Hoyer canal. These canals are lined by modified smooth muscle cells called glomus cells. Essentially, the glomus body functions as a shunt with the capability of increasing or decreasing capillary perfusion of the fingertips and palms.
Glomus tumors arise from glomus cells, however, the fact that glomus tumors exist in locations outside of the fingertips and palms have lead to the theory the tumor cells are derived from perivascular percursor cells with the capability of differentiating glomus cells (Reynolds).
Since they are modified smooth muscle cells, glomus tumors stain positively for SMA and muscle-specific actin.
Occurs in the 3rd to 4th decades with equal sex predilection. Primarily located in the fingers and hands (especially the subungual region) as small red-blue nodules that are painful. The tympanic region may be involved sometimes.
The paroxysmal pain appears to be precipitated by cold or pressure (McKee). This is not surprisingly considering that the glomus body is richly innervated, with thermo-receptors (sensory portion) and arteriovenous shunts (effector portion).
Usually, glomus tumors are isolated lesions. When multiple tumors occur, they generally present in children as an inherited condition.
Excision with clear margins.
Excellent. There are very rare instances recurrence, especially with deep-seated and infiltrative tumors where a clear surgical margin was difficult to obtain.
McKee PH. Pathology of the Skin with Clinical Correlations 2nd Ed. London, UK: Mosby-Wolfe; 1996: 16.76-77.
Reynolds MB. Glomus Tumors eMedicine. Accessed on 8/31/09. Available at http://emedicine.medscape.com/article/1083405-overview