A 40-year-old East Indian man presented with a chronic, recurrent, erythematous rash limited to the inguinal and axillary areas for the past 3 years. The rash was pruritic and at times slightly macerated, and there was no scaling. He treated himself with some over-the-counter medications recommended by his pharmacist, but it was of minimal benefit. Medical history was significant for diabetes mellitus. He did not consume alcohol or smoke. His 65-year-old father had psoriasis.
On examination, there were well-demarcated, thin erythematous plaques in the inguinal and axillary regions. The skin surface was smooth, atrophic, non-scaly, and slightly shiny. He also had pitting of the fingernails. The rest of the physical examination was unremarkable.
Diagnosis of inverse psoriasis is usually clinical, based on the characteristic features. Family history of psoriasis and typical psoriatic lesions in other areas may aid in the diagnosis. A mycologic examination of skin scraping using potassium hydroxide may at times be necessary to differentiate it from fungal intertrigo. A skin biopsy should be considered if the diagnosis is in doubt. In this case, the patient’s presentation was consistent with histological findings of inverse psoriasis, also known as flexural or intertriginous psoriasis.
An anatomic variant of psoriasis, “inverse psoriasis” is characterized by the involvement of skin-fold areas such as the inguinal folds, axillary folds, inframammary folds, retroauricular area, and gluteal cleft rather than the more common psoriatic involvement of the trunk, extensor surfaces of the extremities, and scalp.1 Histologic examination of a classic lesion shows confluent parakeratosis with a loss of the granular layer, epidermal hyperplasia, elongation of rete ridges with thinning of the suprapapillary plates, and dilated capillaries in the dermal papillae with perivascular lymphocytic infiltration.2,3 Munro microabscesses (intracorneal deposits of neutrophils) and Kogoj micropustules (neutrophil deposits in the stratum spinosum), if present, are diagnostic.2
Estimates of prevalence of psoriasis range from 1% to 2%.2 Inverse psoriasis presents in 3% to 7% of psoriatic patients.1,4 The condition most commonly manifests between 15 and 30 years of age.3 Both sexes are affected equally.3 The condition is more common in Caucasian individuals than in black or Asian individuals.2 The prevalence is greatest in northern, colder climates, and the disease is often more severe in the colder months. A family history of psoriasis in a first-degree relative is present in about 30% of patients with childhood-onset psoriasis.5 The concordance rate in monozygotic twins is approximately 70%, compared with 20% in dizygotic twins.5
Etiology and Pathogenesis
This disorder was first described in 1927 by Harry C. Olmsted, MD.4 Approximately 73 cases have been documented since then.3 Cases have been largely sporadic, although a few familial cases have been reported with proposed autosomal dominant, autosomal recessive, or X-linked dominant inheritance patterns.5-7 There appears to be a much higher male prevalence.8,9
Previously, very little had been known about the genetics of Olmsted syndrome; gene sequencing of an affected person revealed no mutations in the genes implicated in other PPKs (including KRT1, GJB2, SLURP1, and LOR).1,7 More recently, various de novo heterozygous dominant and homozygous recessive mutations in the transient receptor potential cation channel, subfamily V, member 3 (TRPV3) gene have been identified in persons with Olmsted syndrome.10-12 Additionally, the membrane-bound transcription factor peptidase, site 2 (MBTPS2) gene has been implicated in the X-linked recessive form of the syndrome.13 The proposed pathogenesis remains unclear, but it may involve a defect in mature epidermal keratin 1 and 10 expression and the persistence of basal keratin 5 and 14, thereby resulting in excessive epithelial proliferation.3,14
Diagnosis, Prognosis, and Management
The cutaneous manifestations of Olmsted syndrome typically allow for a clinical diagnosis. Other genodermatoses featuring PPK (eg, Vohwinkel syndrome, Meleda disease, type II tyrosinemia, pachyonychia congenita, Papillon-Lefévre syndrome) should be considered in the differential, as should psoriasis inversa, chronic mucocutaneous candidiasis, and acrodermatitis enteropathica.1,5 Skin biopsy is not necessary, since results often reveal nonspecific orthohyperkeratosis, acanthosis, hypogranulosis, and chronic inflammatory dermal infiltrate.1,5,9
The clinical manifestations of Olmsted syndrome typically present in the neonatal or childhood period, with variability in disease severity.2 The course is progressive and disabling, and the mutilating nature of the PPK can progress to constriction of the digits or even autoamputation of the fingers and toes. Additionally, these patients have been found to be at increased risk for various epidermal tumors, including squamous cell cancer and malignant melanoma of involved keratotic skin.15-17
The use of various topical and oral treatments have been described in the literature, but with few consistent improvements. Topically, solution of potassium permanganate, salicylic acid, boric acid, urea, tar, retinoic acid, shale oil, corticosteroids, and prolonged soaking or wet dressings have been used with varying success.1,5 Oral retinoids, as well as systemic antihistamines, vitamin E, vitamin A, antimicrobials, and corticosteroids, have been shown to be partially effective in managing the symptoms and progression of the disease.1,18,19 In severe cases, surgical removal of the keratotic plaques with subsequent skin grafting has been attempted in order to reduce pain and improve function; however, the condition recurred in the majority of these cases after initial improvement.20
Olivia L. Quach, AB, is a student at the University of Virginia School of Medicine in Charlottesville, Virginia.
Barbara B. Wilson, MD, is an associate professor and chair of the Department of Dermatology at the University of Virginia School of Medicine in Charlottesville, Virginia.