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What is Glomus tumor and explain in detail?
Glomus tumor was also the name formerly (and incorrectly) used for a tumor now called a paraganglioma.A glomus tumor (also known as a "solitary glomus tumor," "solid glomus tumor,") is a rare neoplasm arising from the glomus body and mainly found under the nail, on the fingertip or in the foot.: 670   They account for less than 2% of all soft tissue tumors. The majority of glomus tumors are benign, but they can also show malignant 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. 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 paragangliomas, 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 manner, with incomplete penetrance.

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.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