Background
Chromhidrosis is a rare condition characterized by the secretion of colored sweat. Two glands produce sweat: eccrine and apocrine glands. Eccrine glands secrete a clear, odorless fluid that serves to regulate body temperature. Apocrine glands secrete a thick, milky sweat that, once broken down by bacteria, is the main cause of body odor.
Chromhidrosis is apocrine in origin. Although apocrine glands are found in the genital, axillary, areolar, and facial skin, chromhidrosis is reported only on the face, [1] axillae, [2] and breast areola. [3, 4] Lipofuscin pigment is responsible for the colored sweat. This pigment is produced in the apocrine gland, and its various oxidative states account for the characteristic yellow, green, blue, or black secretions observed in apocrine chromhidrosis.
In contrast, eccrine chromhidrosis is rare and occurs with ingestion of certain dyes or drugs, and pseudochromhidrosis occurs when clear eccrine sweat becomes colored on the surface of the skin as a result of extrinsic dyes, paints, or chromogenic bacteria.
Approximately 10% of people without chromhidrosis have colored sweat that is regarded as acceptable and within the normal range.
Pathophysiology
Lipofuscin is a yellowish brown pigment that is normally found in the cytoplasm of relatively nondividing cells (eg, neurons). In chromhidrosis, lipofuscins are found in a higher-than-normal concentration or a higher-than-normal state of oxidation in apocrine glands. However, why some glands experience these changes is unclear. This increased level of oxidation results in the green, blue, and even black sweat seen in chromhidrosis.
The yellow, green, and blue apocrine secretions produce a yellow fluorescence under a Wood lamp (UV 360 nm), whereas the dark brown and black apocrine secretions seldom autofluoresce. Substance P is also postulated to be an important neurotransmitter in this process.
Pseudochromhidrosis is of an extrinsic etiology in which a chemical on the surface of the skin reacts with eccrine secretions and produces the color transformation.
Etiology
The increased numbers of lipofuscin pigments in the secretory apocrine cells are presumed to be the cause of apocrine chromhidrosis.
Several extrinsic causes of eccrine chromhidrosis and pseudochromhidrosis include chromogenic bacteria, especially Corynebacterium species, fungi, dyes, drugs, and chemical contactants. [5, 6, 7, 8, 9]
Epidemiology
Frequency
Incidence statistics are not available; chromhidrosis is rare.
Race
Apocrine chromhidrosis appears to be more common in blacks than in whites, but facial chromhidrosis is described only in whites.
Sex
No sexual predilection is reported for chromhidrosis.
Age
Chromhidrosis is noted after puberty, when the apocrine glands are activated. However, rare cases in infants have been reported. [10, 11]
Prognosis
Chromhidrosis persists throughout life, but slow regression of the disease is noted, as apocrine glands regress with time. The prognosis for chromhidrosis is good if an extrinsic cause can be identified and addressed appropriately.
