A 22-year-old female presented with fever, proximal muscle weakness, and polyarthralgia for one month. She presented with a skin rash associated with itching on the upper back, lower back, chest, abdomen, and thighs for a similar duration. She denied any other features suggestive of connective tissue disorders. Cutaneous examination revealed erythematous to dark-brown linear and streaky rash on the back, abdomen, and inframammary area (Figure 1a–d). The rest of the mucocutaneous examination did not reveal any abnormalities. nail fold capillaroscopy revealed no abnormalities. Blood investigations showed microcytic hypochromic anaemia Hb- 8.3 g/dl (normal: 11.7–15.5 g/dL) with leukocytosis (total leukocyte count-14,760 /ul- normal: 4000–11,000 /ul), elevated serum ferritin (1333 ng/ml, normal: 11–306.8 ng/ml), elevated hs-C-reactive protein 147 mg/L (normal: < 3.4 mg/L), erythrocyte sedimentation rate of 125 mm/hr (normal: less than 20 mm/hr)and transaminitis (AST- 100 IU/L (normal:0–50 IU/L), ALT- 122 IU/L (normal: 0–50 IU/L)). Her muscle enzymes were normal, and antinuclear antibodies were negative. A skin biopsy from the rash on the abdomen revealed dyskeratotic cells in the upper epidermis, accompanied by mild acanthosis and hyperkeratosis, with no interface changes (Figure 2). Your diagnosis? … Diagnosis: Persistent pruritic eruption of adult-onset Still's disease Based on the clinical and histopathological findings, a diagnosis of persistent pruritic eruption of adult-onset Still's disease was made. The patient was initiated on tablet prednisolone (1 mg/kg/day). She symptomatically improved, and the steroids were tapered over 3 months and stopped. The lab parameters became within normal limits over the course. (total leukocyte count-9,040 /ul, ferritin-45 ng/mL, ESR-6 mm/hr, AST-23 IU/L and ALT-7 IU/L). The patient did not have a recurrence of the skin rash. The patient is currently under follow-up in immunology for her joint symptoms, and she has been maintained on tablet methotrexate 15 mg/week. Adult-onset Still's disease (AOSD) is a rare, systemic autoinflammatory disorder characterised by quotidian high spiking fevers, arthralgia, leucocytosis, and distinctive skin eruptions. The classic cutaneous manifestation is an evanescent, non-pruritic, salmon-pink rash that appears as confluent erythematous patches during febrile episodes.1, 2 However, recent literature increasingly recognises atypical cutaneous variants, which may aid in diagnosis and prognostication. Among these atypical manifestations are persistent, pruritic eruption (PPE) that often exhibits a violaceous to reddish-brown hue and a scaly, rippled surface. These lesions typically involve the trunk and extremities and are notable for their independence from febrile episodes. Additional uncommon presentations include urticarial lesions, flagellate erythema, and hyperpigmented linear plaques, findings that have been associated with more severe disease phenotypes.1-3 Histopathologically, a distinguishing feature of these atypical eruptions is the presence of dyskeratotic keratinocytes within the upper layers of the epidermis. As reported by Maeda-Aoyama et al., this histologic pattern may correlate with poorer clinical outcomes.3 Importantly, AOSD with PPE can have life-threatening complications, including haemophagocytic lymphohistiocytosis, disseminated intravascular coagulation, and multi-organ failure.1, 2 In this context, PPE may serve as cutaneous markers of disease severity and should prompt careful evaluation. In our case, our patient had a satisfactory response to oral steroids as observed by Pawar et al.3 Given the diverse morphology of AOSD-associated skin lesions, establishing an accurate diagnosis requires exclusion of mimickers. Differential diagnoses for flagellate eruptions include dermatomyositis, bleomycin-induced rash, Chikungunya-related pigmentation, and mushroom poisoning. In the present case, dermatomyositis was ruled out due to the absence of hallmark cutaneous findings such as heliotrope rash, Gottron papules, or Gottron sign. Additionally, the patient demonstrated normal muscle enzyme levels and lacked histopathological evidence of interface dermatitis. Acute cutaneous lupus was similarly excluded based on the absence of characteristic cutaneous features, negative antinuclear antibody testing, and non-supportive histology. Chikungunya virus infection, another important consideration, is often underdiagnosed due to limited awareness among clinicians. Its early dermatologic manifestations typically occurring within the first month of fever include maculopapular eruptions, vesiculobullous lesions, Stevens-Johnson syndrome or toxic epidermal necrolysis-like presentations, flagellate rash, scrotal dermatitis, oro-genital ulcers, and exacerbations of pre-existing dermatoses such as psoriasis. Late-onset cutaneous effects may present as post-inflammatory hyperpigmentation, lichenoid eruptions, diffuse alopecia, or worsening of acne.4 In our patient, none of these features were observed except the flagellate rash, and chikungunya serology was negative. Prurigo pigmentosa (PP) is a rare inflammatory skin condition among the Japanese population marked by the sudden onset of itchy, red papules and plaques that form a reticulated pattern and resolve with mottled hyperpigmentation. It commonly affects symmetrical areas such as the neck, chest, back, and abdomen. Hormonal fluctuations, infections, and external triggers like heat, sweat, sunlight, friction, and allergens are potential contributing factors. A strong association has been found between PP and ketosis-related conditions, including diabetes, fasting, restrictive diets, anorexia nervosa, and post-bariatric surgery.5 Histopathological features of PP include epidermal changes ranging from spongiosis, dyskeratotic cells, basal vacuolar degeneration, interface dermatitis, neutrophilic exocytosis and dermal changes including perivascular lymphocytes and dermal melanophages.6, 7 Bacterial colonies in the follicles and perifolliculitis are also additional features in histology.5 The patient reported no prior application of irritants before the onset of skin lesions. A specific type of dermatosis called granular parakeratosis, related to exposure to irritants like deodorants and antiperspirants, can present as linear pigmented or geometric plaques, histologically showing thickened stratum corneum with parakeratosis and retained keratohyaline granules. In conclusion, persistent pruritic eruptions in AOSD represent a significant but under-recognised clinical entity. Awareness of their distinct clinical and histopathological characteristics is crucial for timely diagnosis and appropriate management of patients with AOSD. None.
Somasundaram et al. (Wed,) studied this question.