Senile gluteal dermatosis: An underrecognized mechanical dermatosis in the elderly

Dear Editor, A 68-year-old male presented with persistent itching and thickened skin over the buttocks for 2 years. Examination revealed well- to ill-defined hyperkeratotic, hyperpigmented plaques measuring approximately 5 cm × 7 cm, with a wrinkled surface and symmetrical triangular distribution over both buttocks [Figure 1]. Routine investigations were unremarkable except for elevated fasting and postprandial blood glucose levels and raised triglycerides. Human immunodeficiency virus, hepatitis B surface antigen, hepatitis C virus tests were negative. Allergic contact dermatitis, lichen simplex chronicus, post-inflammatory hyperpigmentation, and frictional dermatitis were included in the differential diagnoses. A second patient, aged 74 years, presented with similar thickened, wrinkled plaque symmetrically involving both buttocks [Figure 2]. In both cases, lesions within the gluteal cleft were limited to the coccygeal apex, while additional plaques were noted over bony prominences. The chronicity, morphology, and distribution of lesions initially suggested frictional dermatitis; however, on reviewing the literature, the findings were more consistent with senile gluteal dermatosis (SGD). Both patients responded well to a short course of topical mometasone followed by regular emollient use, along with advice to reduce prolonged sitting.Figure 1: Single well-to ill-defined hyperpigmented plaque with surface wrinkling over both buttocks (black arrow)Figure 2: Single ill-defined wrinkled plaque with focal scaling (blue arrow) over bilateral buttocksSGD is an underrecognized friction-induced dermatosis that primarily affects the elderly. Although more frequently reported in East Asian populations, particularly among Korean and Japanese individuals, it is likely underdiagnosed elsewhere. First described by Yamamoto, SGD has been linked to chronic mechanical friction from prolonged sitting or sleeping on firm surfaces such as tatami mats.[1] Clinically, it presents as brownish, hyperkeratotic plaques located above the gluteal cleft and symmetrically over both buttocks, forming the characteristic appearance often described as the three corners of a triangle.[2] SGD is primarily attributed to chronic friction and prolonged pressure. Table 1 summarizes the distinguishing features of other differential diagnoses. Dermatologists frequently encounter friction-related dermatoses such as frictional dermatitis, prayer marks, clothing-induced dermatitis, and frictional melanosis.[3] While hyperpigmentation and hyperkeratosis are common in these conditions, ulceration is uncommon in SGD. Importantly, unlike early pressure ulcers, SGD shows transient, bleachable erythema without evidence of deep tissue necrosis, underscoring its benign and primarily friction-induced nature rather than ischemic damage. Age-related skin changes likely contribute significantly. With advancing age, flattening of the dermo-epidermal junction reduces epidermal resilience and repair capacity, increasing skin fragility. The protective mechanism of pressure-induced vasodilation, which enhances tissue perfusion in response to mechanical stress, also declines with age.[1] In addition, redistribution of body fat – characterized by increased truncal fat and decreased subcutaneous fat over bony prominences – reduces natural cushioning. Elderly males, who often have relatively lower gluteofemoral fat, may therefore be particularly susceptible.[2] Interestingly, the term angiogenesis of the rear and reactive epidermal hyperplasia Reactive Epidermal hyperplasia and Angiogenesis of the Rear (REAR) has been proposed as a broader concept encompassing both prurigiform angiomatosis and SGD, highlighting shared features of chronic friction and reactive epidermal changes.[4] Prurigiform angiomatosis is a benign vascular proliferation due to repeated scratching, characterized by multiple itchy angiomatous papules or nodules that clinically resemble prurigo nodularis.[4] Management is largely conservative. Topical agents such as retinoic acid, mometasone, and calcitriol have shown benefit.[5] Equally important are mechanical and lifestyle measures – avoiding prolonged sitting, using soft cushions, minimizing pressure while lying, and maintaining adequate skin hydration. In conclusion, SGD is a distinct yet frequently overlooked condition that lies at the interface of dermatology and geriatric care. Greater awareness among clinicians is essential to ensure timely recognition, avoid misdiagnosis of early pressure ulcers, and prevent unnecessary interventions.Table 1: The distinguishing features of other differential diagnosesDeclaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given her consent for her images and other clinical information to be reported in the journal. The patient understands that her name and initials will not be published and due efforts will be made to conceal her identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.