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Bromhidrosis
Author: Wingfield Rehmus, MD, MPH,
Coauthor(s): Carol E Cheng, Boston University School of Medicine; Katherine Brown,, Stanford University School of Medicine
Contributor Information and Disclosures
Background
Bromhidrosis, also known as bromidrosis or body odor, is a common phenomenon in postpubertal individuals. In rare cases, bromhidrosis may become pathologic if it isparticularly overpowering or if the bromhidrosis significantly interferes with the lives of the affected individuals. Bromhidrosis is a chronic condition in which excessive odor, usually an unpleasant one, emanates from the skin. Bromhidrosis, determined largely by apocrine gland secretion, can substantially impair a person's quality of life.
Pathophysiology
Types of glands and their functions
Humansecretory glands are primarily divided into 2 types: apocrine and eccrine.
Eccrine glands are distributed over the entire skin surface, where they are involved in thermoregulation by means of sweat production.
In contrast, apocrine glands have a limited distribution involving the axilla, genital skin, and breasts. Apocrine elements are also found in the periorbital and periauricular areas.Apocrine glands have no thermoregulatory role but are responsible for characteristic pheromonal odors.
They secrete a small amount of oily fluid, which is odorless upon reaching the skin surface. The characteristic odor is due to bacterial decomposition of the oily fluid.1,2 Studies have shown that in comparison to controls, individuals with bromhidrosis display more numerous and larger apocrineglands.
Lastly, apoeccrine glands are sweat glands that become apparent between the ages of 8 and 14 years. They are functionally and pharmacologically distinct from apocrine glands and contribute heavily to overall axillary sweating. They develop during puberty from eccrinelike precursor glands.
* Histological findings suggest that eccrine glands are dominant in the dermis, but most apocrineglands are located in the subcutaneous tissue, although the definite location is not yet known.
Control of apocrine glands
Current evidence suggests that the human apocrine gland appears to be under sympathetic nervous control with the peripheral mechanisms regulated by catecholamines. The presence of purinergic receptors within the gland also indicates the use of a secondary sudomotor pathway withnucleotide involvement in the secretory glands.3

Apocrine bromhidrosis
Apocrine bromhidrosis is the most prevalent form of bromhidrosis and should be differentiated from the less common eccrine bromhidrosis. Several factors contribute to the pathogenesis of apocrine bromhidrosis. Bacterial decomposition of apocrine secretion yields ammonia and short-chain fatty acids, with theircharacteristic strong odors. The most abundant of these acids is (E)-3-methyl-2-hexanoic acid (E-3M2H), which is brought to the skin surface bound by 2 apocrine secretion odor-binding proteins, ASOB1 and ASOB2. ASOB2 has been identified as apolipoprotein D (apoD), a known member of the lipocalin family of carrier proteins.4,5,6

Axillary bacterial florae have been shown to produce the distinctive axillaryodor by transforming nonodoriferous precursors in sweat to more odoriferous volatile acids. The most common of these are E-3M2H and (RS)-3-hydroxy-3-methlyhexanoic acid (HMHA), which are released through the action of a specific zinc-dependent N -alpha-acyl-glutamine aminoacylase (N-AGA) from Corynebacterium species. This aminoacylase has been demonstrated to also release other odoriferous acidsfrom glutamine conjugates in sweat, which may be the basis of individual body odor.7

Eccrine bromhidrosis
In certain circumstances, eccrine secretion, which is typically odorless, assumes an offensive aroma and causes eccrine bromhidrosis. When eccrine sweat softens keratin, bacterial degradation of the keratin yields a foul smell. Ingestion of some foods, including garlic, onion, curry,...
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