290 Evaluating clinical features and the presence of eosinophilia in pityriasis rubra pilaris

Abstract

Pityriasis rubra pilaris (PRP) is a rare disease presenting with orange to salmon-colored folliculocentric papules on the trunk and extremities, waxy palmoplantar keratoderma, and hyperkeratotic nails. PRP literature remains limited, and its pathogenesis remains unclear, often resulting in missed or delayed diagnosis. Further, although a case study found eosinophilia in a PRP patient, hematologic abnormalities have not been extensively examined, sparking the interest to evaluate for an association between eosinophilia and PRP to enhance diagnosis. PRP patients from 1980-2020 at Mass General Brigham were identified. Demographics, disease presentation, and laboratory and pathology data were recorded. This study was approved by the Brigham and Women’s Hospital IRB. Student t-test and chi-square analysis were conducted to evaluate for differences; p<0.05 was considered significant. 142 PRP patients were identified (55% male, 85% white); 82% were categorized as Type 1. 19.7% had eosinophilia in serum or skin biopsy. Age at presentation for patients with and without eosinophilia was 60.8±14.6 and 53.1±19.7, respectively (p=0.03). Presenting symptoms included pruritus (33%), ocular dryness (4%), and hair thinning (4%). Lesions were present in the extremities (49%), trunk (43%), and head and neck (33%). Common biopsy findings included sparse superficial dermal perivascular lymphohistiocytic infiltrate (39%) and alternating ortho-/parakeratosis (37%). There were no significant differences in patient sex, race, disease presentation, or biopsy findings between the eosinophilia and non-eosinophilia cohorts. This study is the largest PRP study to date. Nearly 20% of PRP patients had eosinophilia at diagnosis and therefore, the presence of peripheral or biopsy-eosinophilia at diagnosis highlights an association that may suggest potential treatment strategies or help elucidate the underlying pathophysiology of this rare condition.