Pseudochromhidrosis is an extremely rare pathology of the eccrine sweat glands. Patients produce colorless sweat that subsequently becomes colored when being in contact with various external compounds, which leads to black, blue, pink, brown, yellow, or red discoloration of the skin. The diagnosis rests on a thorough patient history and a comprehensive laboratory workup.
Pseudochromhidrosis is a rare phenomenon in clinical practice, with only a handful of cases described in the literature so far   . The coloration of the skin seen in these individuals stems from the initial production of uncolored sweat that interacts with various substances present on the skin   . Changes in sweat color have been associated with bacterial pathogens (Corynebacterium sp., Malassezia furfur, Bacillus sp., Serratia marcescens), fungi, drugs, chemical products (topiramate, gold salts, emollients, and tanning creme have been confirmed as causes), and clothing dyes     . Irritant contact dermatitis and subsequent use of systemic corticosteroids (that were assumed to aggravate the symptoms) are also noted as possible etiology . Up to this point, patients have presented with red, black, blue, brown, yellow, and pink color sweat and virtually any site in the body can be affected     . Reports documented isolated coloration of the face, palms, toe webs, and toenails  , whereas generalized changes have also been observed    . Age is not a relevant factor in the appearance of pseudochromhidrosis, as this condition is encountered in children, young adults, and the elderly     . Except for perioral irritation seen in one patient that suffered from the red coloring of the face, accompanying signs or color changes of other fluids or tissues (saliva, urine, blood, feces, etc.) are absent     . Because of the extrinsic nature of pseudochromhidrosis, it is self-limiting and resolves after elimination of the underlying cause.
Because of the rare occurrence of pseudochromhidrosis, clinicians will unlikely encounter this disorder. For this reason, the physician must conduct a thorough investigation in the presence of skin discoloration. Firstly, a detailed patient history is necessary to cover the recent use of pharmacological agents and changes in treatment for pre-existing disorders. Clothing marks are sometimes reported by patients, which may be a useful clue toward the diagnosis   . The physical examination is crucial for determining the exact area(s) of skin changes and follow-up laboratory studies need to be conducted. Exams like a complete blood count (CBC), basic biochemistry and urinalysis should be included in the initial workup . The role of microbial agents in the development of pseudochromhidrosis necessitates the use of skin cultures (for both bacteria and fungi), with a goal of identifying the underlying cause  . In some cases, however, a favorable response to antimicrobial therapy has been confirmed in the absence of a positive culture . A skin biopsy can be used as a definitive diagnostic method, showing dilated apocrine acini with a colored secretion  .