Rare syndromes with dermatologic symptoms can be associated with focal hyperhidrosis. In POEMS syndrome, seen primarily in the Japanese population, patients have polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes accompanied by hyperhidrosis. Several subtypes of a rare ectodermal dysplasia, pachyonychia congenita, are associated with palmoplantar hyperhidrosis, as is pachydermoperiostosis, in which patients appear to have acromegaly with finger clubbing, periosteal new bone formation, and coarsened facial features. Hyperhidrosis can also be seen with nail-patella syndrome, a disorder involving hypoplastic nails, bony abnormalities including hypoplastic patellae, and renal disease.
Hyperhidrosis can be seen in skin overlying a blue rubber bleb nevus and in skin adjacent to glomus tumors. Localized sweating around these types of lesions as well as painful skin ulcers may be the basis of axon-reflex sweating. This type of sweating is due to a direct axon reflex that occurs around the border of painful lesions.
In an idiopathic form of excessive sweating, localized unilateral hyperhidrosis (LUH), excessive sweating occurs in a small area of the forehead or forearm. This rare type of hyperhidrosis differs from primary hyperhidrosis in that there are no triggers. Sweating occurs spontaneously and during sleep. One theory is that LUH is caused by “a misdirected reconnection of the sympathetic nerve fiber network after injury, similar to Frey syndrome.”
A functional nevus has also been found to be associated with focal hyperhidrosis. A nevus sudoriferus, located on the face or forearms, excretes excessive sweat in response to thermal or emotional triggers. These nevi can be linear or circular and of varying size. Histologic exam reveals hyperplastic eccrine glands but only rarely increased numbers of glands. There are several case reports of localized unilateral hyperhidrosis caused by this type of nevus.[78,107]