Black-Hued Pseudochromhidrosis on Digits

Chromhidrosis is a well-documented disorder characterized by the secretion of colored sweat due to various pigments, such as lipofuscin or porphyrins, in the apocrine or eccrine glands. Apocrine chromhidrosis is characterized by lipofuscin pigment produced in apocrine glands and its oxidative state, accounting for the various hues of sweat secreted through the skin.¹ Patients with apocrine chromhidrosis are often affected in localized areas such as the face, areola, or axillae due to greater lipofuscin concentrations or oxidative states.² Unlike apocrine chromhidrosis, eccrine chromhidrosis is not locally restricted and most commonly occurs when the water-soluble pigments in specific dyes and drugs are ingested, such as quinine and beta-carotene.^1,3

Pseudochromhidrosis, however, is distinguished by excretion of colorless sweat that acquires a noticeable hue upon contact with external agents, often leading to diagnostic confusion.¹ Pseudochromhidrosis may affect any part of the body, but most commonly involves the face, palms, and neck.⁴ Common extrinsic causes of pseudochromhidrosis include paints; chemical dyes; and chromogenic microorganisms such as Corynebacterium, Pseudomonas aeruginosa, and Piedraia. ^3,5

This case report presents the clinical course of a 28-year-old woman with pseudochromhidrosis. Differentiating between chromhidrosis and pseudochromhidrosis is crucial for appropriate management and subsequent improvement in quality of life.

Case Presentation

A 28-year-old woman presented with a 1-day history of skin discoloration. Upon initial presentation, the patient described her skin changes as black-hued patches that had appeared on her hands and fingertips and were first noticed upon awakening for the day. No associated symptoms, such as pain, odor, pruritus, inflammation, or systemic symptoms, were noted by the patient. She also denied any recent occupational exposures or changes to medications or skin care regimens. Past medical history, family history, social history, and surgical history were all unremarkable. The patient denied changes in the color of her tears, saliva, nasal secretions, or urine.

Physical examination revealed an otherwise healthy-appearing patient with no evidence of jaundice or other dermatologic abnormalities noted. Black-hued patches were noted on the acral surfaces of the fingers with sparing of the thumbs (Figure 1). A dermoscopic examination was conducted, which revealed extensive superficial black pigmentation on the stratum corneum (Figure 2). Pigment was noted to accentuate around the openings of the eccrine ducts located on the ridges of the fingers. The pigment was lightened after being cleansed with an alcohol pad. Diagnosis of pseudochromhidrosis was then subsequently made through patient history, physical examination, and dermoscopic findings.

After a detailed evaluation and history taking, it was determined that the resulting pseudochromhidrosis was caused by contact with a black-dyed book cover that the patient had been reading before going to bed the night before presentation. Figure 3 demonstrates how the patient held the book, which precisely mimics the distribution of her discoloration and the subsequent reason for the sparing of any pigment on her thumbs. Ultimately, our patient’s pseudochromhidrosis resolved over the following day with vigorous hand washing and did not recur after subsequent physical avoidance of the book cover through the application of a book sleeve before holding the book. Figure 4 displays the progressive resolution of pigment within 24 hours after thorough cleansing and noncontact with the trigger.

Discussion

Chromhidrosis can be either apocrine or eccrine in etiology. Apocrine chromhidrosis is diagnosed through skin biopsy revealing lipofuscin granules in an oxidized state, which results in the change in sweat color. Treatment of apocrine chromhidrosis can include pharmacologic measures such as capsaicin, botulinum toxin, or topical aluminum chloride for symptomatic relief.^6,7 Manual pressure can also be utilized to express apocrine secretions and empty out the glands for a temporary symptom-free period. Despite this, apocrine chromhidrosis may be taxing on the patient because it typically recurs after discontinuation of therapy.^6,7 Eccrine chromhidrosis is considered a diagnosis of exclusion as it relies on a patient history of prior ingestion of chemicals or dyes.⁸ Treatment for eccrine chromhidrosis involves cessation of the underlying agent responsible.⁶ Many cases of apocrine and eccrine chromhidrosis have been reported, including red, green, and blue discolorations of sweat.^9-11 Another differential diagnosis to consider for pigmentation changes on the skin is ochronosis. Often caused by alkaptonuria, ochronosis results in a bluish-black discoloration of skin and cartilage due to a deficiency of homogentisic acid oxidase, thus causing a deposition of certain substances.¹²

Pseudochromhidrosis, characterized by transient sweat discoloration upon contact with external substances, is a rare phenomenon that can mimic chromhidrosis and other pigmenting conditions. Unlike chromhidrosis, which involves the excretion of pigmented sweat, pseudochromhidrosis stems from a chemical reaction occurring in clear sweat. The most common extrinsic causes of pseudochromhidrosis are chromogenic bacteria such as Bacillus spp., Serratia marcescens, and Corynebacterium spp. ⁴ Other known etiologies of pseudochromhidrosis include drugs, such as topiramate or lansoprazole; dyes from clothing; and chemical agents, such as dihydroxyacetone or self-tanning agents.⁴

After our patient presented with discolored patches on her fingers, we made a diagnosis through a thorough history, which revealed contact with a black-dyed book cover, combined with dermoscopic findings of prominent pigmentation near the openings of eccrine ducts on the acral skin ridges. Other cases of pseudochromhidrosis may require a more extensive work-up, such as skin cultures or biopsies, to discover the underlying cause and rule out other conditions.^13,14

Treatment for pseudochromhidrosis is dependent on the precipitating etiology. For cases of infectious pseudochromhidrosis, oral erythromycin combined with topical erythromycin for 1 to 2 weeks appears to be the most effective regimen.⁴ For cases of noninfectious pseudochromhidrosis, effective treatment typically consists of removal of the triggering agent, barrier protection of the skin, and cleansing of the affected areas. Differentiating these conditions is vital to prevent unnecessary investigations and costly interventions. Although pseudochromhidrosis provides no downstream or systemic health concerns, it may cause discomfort and distress to those affected by it.

Conclusion

Awareness of pseudochromhidrosis and its distinction from chromhidrosis is essential for accurate diagnosis and management. This case underscores the importance of considering this condition in sweat-related discoloration, as well as other forms of cutaneous pigmentary alteration, potentially leading to improved patient care.

Whitney Vaughan is an MS-III in the research division at Alabama College of Osteopathic Medicine in Dothan, AL. Jay Modi is an MS-III in the Office of Medical Student Research at Oklahoma State University Center for Health Sciences in Tulsa, OK. Dr Howard is a dermatologist at Utica Park Clinic Dermatology in Tulsa, OK.

Disclosure: The authors report no relevant financial relationships

References

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9. Yöntem A, Kör D, Hızlı-Karabacak B, Karakaş M, Önenli-Mungan N. Bluecolored sweating: four infants with apocrine chromhidrosis. Turk J Pediatr. 2015;57(3):290-293.

10. Jaiswal AK, Ravikiran SP, Roy PK. Red eccrine chromhidrosis with review of literature. Indian J Dermatol. 2017;62(6):675. doi:10.4103/ijd.IJD_755_16 1

1. Ghosh SK, Rudra O, Kar R, Ghosh A, Agarwal M. A curious case of blue-green discoloration in a middle-aged Indian man: chromhidrosis. Dermatol Online J. 2015;21(11):13030/qt5jj4859x.

12. Ochronosis. American Osteopathic College of Dermatology. Accessed January 6, 2024. https://www.aocd.org/page/Ochronosis

13. Nair PA, Kota RKS, Surti NK, Diwan NG, Gandhi SS. Yellow pseudochromhidrosis in a young female. Indian Dermatol Online J. 2017;8(1):42-44. doi:10.4103/22295178.198778

14. Rodríguez-Martín M, Rodríguez MS, Cabrera AN. Palmar and digital black pseudochromhidrosis: a case report. Int J Dermatol. 2010;49(5):562-564. doi:10.1111/ j.1365-4632.2010.04353.x

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