Atypical Lupus Erythematosus Profundus of the Flank Evaluated by Serial Computed Tomography and Managed with Hydroxychloroquine: A Case Report.

INTRODUCTION: Lupus erythematosus profundus (LEP) is a rare form of chronic cutaneous lupus erythematosus that predominantly involves the subcutaneous adipose tissue. When it presents at an atypical site, LEP may mimic infection or neoplasia, delaying diagnosis. CASE PRESENTATION: A 37-year-old woman presented with a progressively enlarging ulcerated indurated lesion on the left flank. An initial biopsy performed at another hospital raised concern for a lymphoproliferative disorder. Computed tomography (CT) demonstrated panniculitic changes in the left flank and additional clinically occult lesions in the right buttock and left thigh. An incisional biopsy from the thigh, selected on the basis of the CT findings, showed interface dermatitis, lymphoplasmacytic panniculitis, dermal mucin deposition, and granular IgM deposition along the dermoepidermal junction, supporting a diagnosis of LEP and arguing against cutaneous lymphoma. Treatment with prednisolone followed by adjunctive hydroxychloroquine (HCQ) led to ulcer healing and radiologic improvement, allowing gradual corticosteroid tapering without relapse to date. CONCLUSION: This case underscores the importance of considering LEP in atypical deep truncal lesions. In this patient, CT was useful for defining disease extent, identifying clinically occult lesions, selecting a biopsy site, and documenting treatment response. HCQ may also be a useful steroid-sparing adjunct in LEP.