Lupus panniculitis in a 9 year-old girl: a case report

Introduction: Lupus panniculitis (LP) is a rare variant of cutaneous lupus erythematosus. LP commonly presents in the third-to-sixth decades of life, with female predilection. The most common cutaneous manifestations are tender, painful, erythematous subcutaneous indurated nodules or plaques on fatty body areas. Profound lipoatrophy often occurs, potentially leading to severe disfigurement. While LP is frequently isolated, coexistence with discoid lupus erythematosus (DLE) or systemic lupus erythematosus (SLE) may occur. In children diagnosed with LP, the risk of progression to SLE is unknown. Diagnosis is often delayed, increasing the risk for sequalae, such as atrophy and calcinosis. Differential diagnosis for LP includes many diseases such as erythema nodosum, pancreatic panniculitis, morphea profunda, cold-panniculitis and subcutaneous panniculitis-like T-cell lymphoma (SPTCL), which may be clinically identical with LP. LP is commonly treated with antimalarial drugs, immunosuppressants and corticosteroids. Objectives: To report a rare case of a 9 year old girl diagnosed with LP. Methods: A nine year old girl came to our department because of painful erythematosus nodules in her left leg from six months. It was not referred history of fever or trauma. Patient examination revealed erythematous, nodular lesion with microulcerations affecting the left leg. The left limb was flexed and extra-rotated. Patient presented intense pain and lameness on walking. The rest of clinical examination was unremarkable. Complete blood count, inflammatory parameters, liver, kidney function, iron levels was in the norm. Both Antinuclear antibodies and ENA were negative. Virological screening (including Sars-Cov2) was negative. Quantiferon test was negative. Urinalysis was in the norm. Faecal calprotectin was negative. Both heart and abdomen ultrasound were in the norm. Patient underwent to magnetic resonance of left leg and skin biopsy of the lesion. Results: MRI revealed: signal hypertensity of skin tissue and subcutaneous adipose tissue in the left thigh. A further area of ​​hyperintensity in correspondence with the cutaneous plane at the level of the popliteal fossa and the subcutaneous tissue and two areas of signal hyperintensity affecting the semitendinosus and sartorius muscle were also detected. Skin biopsy showed: superficial and deep perivascular lymphocytic dermatitis (prevalence of CD3 + T lymphocytes with predominance of CD4 +) with lobular panniculitic involvement prevailing at the dermo-hypodermic interface. Conclusion: According to clinical features, laboratory, radiological and histopathological findings Lupus Panniculitis was diagnosed and treatment with prednisone and methotrexate was started. At a one month follow up visit patient was in good general conditions, she was able to walk. The erythematous nodules were in regression. Lupus panniculitis is rare and difficult to diagnose, particularly in patients without SLE or DLE at presentation. An early diagnosis is very important in order to start an adequate treatment avoiding complications, such as pain and irreversible atrophy