GLOMUS TUMOR AND
GLOMANGIOMA
Glomus tumors are benign
tumors derived from the glomus body. The glomus body is a component of the
vascular thermoregulatory unit. These tumors are most frequently encountered in
early adulthood and are most commonly found on the digits. Glomus tumors are
solitary in nature, and the term glomangioma is used when describing the
glomuvenous malformation. This usually manifests as a congenital defect in
infants and young children and appears to be a multifocal grouping or mass of
coalescent glomus tumors.
Clinical Findings: The solitary glomus tumor is often found
on the digit in a subungual location. The tumors occur equally in men and in
women. Lesions have been described in all regions of the skin and also in
extracutaneous locations. These tumors are small, well localized, and almost
always tender or painful. The glomus tumor is in the differential diagnosis of
the painful dermal nodules. On examination, one often observes a 1- to 2-cm,
well-circumscribed, blue to purple dermal nodule. It is tender to palpation and
can be extremely painful with changes in the ambient temperature.
Glomangiomas are frequently congenital and manifest as a multifocal
cluster of coalescing, blue-purple nodules and papules. There is occasionally
some surface change over the top of the tumors. The Hildreth sign is a
diagnostic maneuver that can be used to help make the diagnosis. The sign is
positive if the pain from the glomus tumor decreases or disappears when a blood
pressure cuff is placed proximal to the tumor and inflated to a pressure
greater than the patient’s systolic blood pressure. Glomangiomas can be
confused with hemangiomas or other vascular malformations. The differential
diagnosis of a solitary glomus tumor includes angiolipoma, neuroma, eccrine
spiradenoma, leiomyoma, and vascular tumors. The differential diagnosis of a
glomangioma includes hemangiomas and other vascular malformations.
Histology: The tumor manifests as a wellcircumscribed
nodule of glomus cells surrounding a number of small capillaries. The glomus
cells are distinctive and uniform. They appear round and have round nuclei. The
cytoplasm is scarce and eosinophilic. The background stroma is myxoid, and
there is often a fibrous capsule surrounding the entire tumor.
Pathogenesis: Glomus tumors arise from the SucquetHoyer
canal. This canal is an arteriovenous shunt found in the small vasculature of
the skin. These canals have been found in a higher density within the blood
vessels of the digits. They are responsible for thermoregulation and cause
shunting of blood in response to neurological and temperature changes. The
exact initiating factor is unknown. Anecdotal reports of glomus tumors occurring
after trauma have led some to believe that trauma is causative. This may
explain the preponderance of the tumors
on the digits, where they are prone to trauma. Trauma is unlikely to be the
true initiating factor, because these tumors are quite rare and trauma to the
digits occurs frequently.
Some glomangiomas have been described to be inherited in an autosomal
dominant fashion. These cases are caused by a deletion defect in the glomulin
(GLMN) gene, which is located on the short arm of chromosome 1. The exact
function of the protein encoded by
this gene or how its defect causes glomangiomas is still not understood.
Treatment: Glomus tumors are successfully treated with
complete surgical excision. Glomangiomas, because of their size, can be excised
in a staged approach or with the help of tissue expanders. Reports of treatment
with laser ablation, electrocauterization, and sclerotherapy, with some
success, have been documented in the literature.
