Journal of Clinical Cases

Mimicking The “Great Imitator”: Pityriasis Rubra Pilaris Misdiagnosed As Systemic Lupus Erythematosus: A Case Report

Ioana Burciu¹, Mihai Augustin Oprea¹Viviana-Cristina Pavel ¹, Valer Mihai Pompilian^1,3, Daniela Nestor^1,3,Razvan Theodor Andrei¹

1. 3rd Internal Medicine Department, Colentina Clinical Hospital, Bucharest, Romania.
2. Pathological Anatomy Department, Colentina Clinical Hospital, Bucharest, Romania.
3. “Carol Davila” University of Medicine and Pharmacy, Bucharest.

Corresponding Author: Ioana Burciu, 3rd Internal Medicine Department, Colentina Clinical Hospital, Bucharest, Romania

ABSTRACT

Pityriasis rubra pilaris (PRP) is a rare skin condition, currently classified as a keratinization disorder. It is associated with various malignancies and autoimmune diseases. There are six clinical subtypes and can affect both adults and children. Due to its rarity, is often initially misdiagnosed and mistreated. We present a case of a 53-year-old woman with PRP who was initially misdiagnosed as systemic lupus erythematosus (SLE) and treated accordingly. In our case, both the clinical signs and the laboratory testing (minor lymphopenia, positive results for both antinuclear antibodies (ANA) and anti-dsDNA antibodies) suggested a diagnosis of SLE. Treatment consisting in Prednisone 10 mg/d and Plaquenil 400 mg/d was initiated. One month after Plaquenil was introduced, patient returned to the clinic with generalized erythrodermic eruption and a severe cutaneous adverse drug reaction (post-Plaquenil) was suspected. Skin biopsy revealed hyperkeratosis with areas of parakeratosis, mild acanthosis and small foci of perivascular lymphocytic inflammation within the papillary dermis leading to the diagnosis of PRP. Following the dermatologist`s recommendation, Methotrexate 15 mg/week via subcutaneous injection was started. Prednisone was gradually tapered and discontinued with complete resolution of skin lesions at 2 months of treatment. The preliminary hypothesis concerning a post-Plaquenil eruption was ruled out based on the duration of eruption following discontinuation of the drug. In this patient’s case, no underlying malignancy or autoimmune disease could be identified. This case report highlights the importance of skin biopsy whenever there is suspicion of PRP and emphasises the possibility of systemic presentation of this rare skin condition