:''Glomus tumor was also the name formerly (and incorrectly) used for a tumor now called a

paraganglioma A paraganglioma is a rare neuroendocrine neoplasm that may develop at various body sites (including the head, neck, thorax and abdomen). When the same type of tumor is found in the adrenal gland, they are referred to as a pheochromocytoma. They a ...

.'' A glomus tumor (also known as a "solitary glomus tumor," "solid glomus tumor,") is a rare

neoplasm A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...

arising from the glomus body and mainly found under the nail, on the fingertip or in the foot.Freedberg, et al. (2003). ''Fitzpatrick's Dermatology in General Medicine''. (6th ed.). McGraw-Hill. . They account for less than 2% of all soft tissue tumors. The majority of glomus tumors are

benign Malignancy () is the tendency of a medical condition to become progressively worse. Malignancy is most familiar as a characterization of cancer. A ''malignant'' tumor contrasts with a non-cancerous ''benign'' tumor in that a malignancy is not s ...

, but they can also show

malignant Malignancy () is the tendency of a medical condition to become progressively worse. Malignancy is most familiar as a characterization of cancer. A ''malignant'' tumor contrasts with a non-cancerous ''benign'' tumor in that a malignancy is not s ...

features. Glomus tumors were first described by Hoyer in 1877 while the first complete clinical description was given by Masson in 1924. Histologically, glomus tumors are made up of an afferent arteriole, anastomotic vessel, and collecting

venule A venule is a very small blood vessel in the microcirculation that allows blood to return from the capillary beds to drain into the larger blood vessels, the veins. Venules range from 7μm to 1mm in diameter. Veins contain approximately 70% of ...

. Glomus tumors are modified smooth muscle cells that control the thermoregulatory function of dermal glomus bodies. As stated above, these lesions should not be confused with

s, which were formerly also called glomus tumors in now-antiquated clinical usage. Glomus tumors do not arise from glomus cells, but paragangliomas do. Familial glomangiomas have been associated with a variety of deletions in the GLMN ( glomulin) gene, and are inherited in an

autosomal dominant In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant and t ...

manner, with

incomplete penetrance Penetrance in genetics is the proportion of individuals carrying a particular variant (or allele) of a gene (the genotype) that also express an associated trait (the phenotype). In medical genetics, the penetrance of a disease-causing mutation is t ...

Signs and symptoms

Glomus tumors are usually solitary and small lesions. The vast majority are found in the hand, wrist, foot, and under the

fingernails A nail is a claw-like plate found at the tip of the fingers and toes on most primates. Nails correspond to the claws found in other animals. Fingernails and toenails are made of a tough protective protein called alpha-keratin, which is a polymer ...

. They are often painful, and the pain is reproduced when the lesion is placed in cold water. Multiple tumors are less likely to be painful. These tumors tend to have a bluish discoloration, although a whitish appearance may also be noted. Elevation of the nail bed can occur. In rare cases, the tumors may present in other body areas, such as the gastric antrum or

glans penis In male human anatomy, the glans penis, commonly referred to as the glans, is the bulbous structure at the distal end of the human penis that is the human male's most sensitive erogenous zone and their primary anatomical source of sexual pl ...

. Treatment is essentially the same. Malignant glomus tumors, or

glomangiosarcoma Glomangiosarcoma is a low grade tumor of the soft tissue. They rarely metastasize, but metastases are possible. It is also known as "malignant glomus tumor". Positive staining for vimentin has been reported. See also * angiosarcoma Angiosarcoma ...

s, are extremely rare and usually represent a locally infiltrative malignancy. However, metastases do occur and are usually fatal.

Diagnosis

Cancerous glomus tumors are exceedingly rare. Criteria for the diagnosis of malignancy in glomus tumors are: # Tumor size of more than 2 centimeters and subfascial or visceral location. # Atypical mitotic figures. # Marked nuclear atypia and any level of mitotic activity. #*

Pericytes Pericytes (previously known as Rouget cells) are multi-functional mural cells of the microcirculation that wrap around the endothelial cells that line the capillaries throughout the body. Pericytes are embedded in the basement membrane of blood c ...

of Zimmerman Cancerous glomus tumors have been subdivided into three categories based on their histologic appearance: locally infiltrative glomus tumors (LIGT), glomangiosarcomas arising in benign glomus tumors (GABG), and glomangiosarcomas arising de novo (GADN). A few cases of cancerous glomus tumors have been reported; however, they are usually only locally invasive, and metastases are exceedingly rare. There is one report of widespread metastases of a malignant glomus tumor involving the skin, lungs,

jejunum The jejunum is the second part of the small intestine in humans and most higher vertebrates, including mammals, reptiles, and birds. Its lining is specialised for the absorption by enterocytes of small nutrient molecules which have been previou ...

, liver, spleen, and lymph nodes. Another report of a malignant glomus tumor (

) with metastases from the skin. A malignant glomus tumor one arose from the kidneys.

Differential

The probable misdiagnosis of many of these lesions as

hemangioma A hemangioma or haemangioma is a usually benign vascular tumor derived from blood vessel cell types. The most common form, seen in infants, is an infantile hemangioma, known colloquially as a "strawberry mark", most commonly presenting on the ski ...

s or venous malformations also makes an accurate assessment of incidence difficult.

Treatment

2011 May Glomus Tumor Extraction Closeup

Surgical excision is the preferred treatment for benign glomus tumors.

Epidemiology

The exact rate of glomus tumors is unknown. The multiple variant is rare, accounting for less than 10% of all cases.

Sex

Solitary glomus tumors, particularly subungual lesions, are more common in females than in males. Multiple lesions are slightly more common in males.

Age

Solitary glomus tumors are more frequent in adults than in others. Multiple glomus tumors develop 11–15 years earlier than single lesions; about one third of the cases of multiple tumors occur in those younger than 20 years. Congenital glomus tumors are rare; they are plaguelike in appearance and are considered a variant of multiple glomus tumors.

References

External links

* * {{Vascular tumors Dermal and subcutaneous growths Types of neoplasia Soft tissue tumor