What is pseudochromhidrosis, including its causes, diagnosis, and management?

Pseudochromhidrosis

Pseudochromhidrosis is a benign condition where initially colorless sweat acquires color after contact with chromogenic bacteria, dyes, or chemical agents on the skin surface—not from pigmented secretion by the sweat glands themselves. 1

Definition and Pathophysiology

Pseudochromhidrosis differs fundamentally from true chromhidrosis in that the sweat is colorless when secreted but becomes pigmented externally. 1 The coloration occurs when normal sweat interacts with:

• Chromogenic bacteria (most common cause): Four specific bacteria produce characteristic colors—Bacillus spp. (blue), Corynebacterium spp. (brown/black), Serratia marcescens (red/pink), and Pseudomonas aeruginosa (blue-green) 2
• Exogenous dyes from clothing or cosmetics 1
• Chemical agents applied to the skin 1

The bacterial pigments result from evolutionary competition among microorganisms and appear decisive in their survival, pathogenicity, and virulence. 2

Clinical Presentation

The hallmark diagnostic feature is that the pigmentation is easily removable by rubbing with a moist compress, leaving normal-colored skin and transferring the pigment to the compress. 3 Key clinical characteristics include:

• Pigmentation typically recurs within 2 hours after removal 3
• Most commonly affects the face (nose, forehead, perioral region, cheeks) but can occur on any body surface 3
• Causes significant psychological stress and social embarrassment despite being medically benign 4
• Most frequently diagnosed in young adults, though pediatric cases occur 5
• Familial cases have been reported, suggesting possible genetic predisposition to bacterial colonization patterns 5

Diagnostic Approach

Begin with bacteriological culture by rubbing the affected skin areas with a sterile swab to identify chromogenic organisms. 3 The diagnostic algorithm should proceed as follows:

1. Confirm removability: Test whether pigmentation can be wiped away with moist compress, leaving normal skin 3
2. Obtain bacterial cultures: Sample affected areas by rubbing with sterile swabs 3
3. Review exposures: Systematically eliminate exogenous dyes (clothing, cosmetics) and chemical agents 1
4. Assess triggers: Evaluate for medications or conditions causing physiological alterations or changes in skin microflora 2

Skin biopsy is not essential as first-line investigation when bacterial etiology is suspected, but may be considered if antibiotic therapy fails. 3 Common commensal bacteria identified include Actinomyces viscosus, Staphylococcus epidermidis, Cutibacterium acnes, and Streptococcus sanguinis. 3

Treatment Algorithm

Topical and oral erythromycin is the most effective treatment for both identified and unidentified chromogenic bacterial cases. 1 Treatment should follow this sequence:

First-Line Approach

• Remove all exogenous sources: Eliminate dyes from clothing and chemical agents first 1
• Initiate antibiotic therapy: Even with negative bacteriological testing, antibiotic therapy is indicated as a therapeutic test 3
• Prescribe erythromycin: Both topical and oral formulations show excellent efficacy 1

Alternative Antimicrobial Options

• Antiseptic therapies can be used as adjunctive treatment 2
• Address any identified physiological triggers or medications that may alter skin microflora 2

Prognosis and Follow-up

Results are excellent with complete resolution and no recurrence when appropriate treatment is implemented. 1 The condition is entirely benign from a medical standpoint, though the psychological impact warrants prompt treatment. 4

Key clinical pitfall: Do not delay antibiotic therapy while awaiting culture results, as bacterial pseudochromhidrosis responds well to empiric erythromycin even when cultures are negative or show only normal skin flora. 3 The presence of commensal bacteria does not exclude the diagnosis, as these organisms can become chromogenic under certain conditions. 3