Supplementary Material for: Multiple Primary Cutaneous Anaplastic Large Cell Lymphoma: A Case Report

Introduction: Anaplastic large cell lymphomas (ALCL) are a subtype of non-Hodgkin lymphoma categorized into systemic and cutaneous (cALCL) subtypes. cALCL are frequently characterized by their lack of ALK receptor expression, which differentiates them from their systemic counterparts. cALCLs present as solitary or grouped skin lesions. Due to their rarity, cALCLs are frequently misdiagnosed as other skin conditions. Case presentation: We report the case of a female with a 30-year history of expanding skin lesions on the upper and lower limbs, abdomen, and back. During her initial presentation, the lesions were thought to be due to an arthropod bite. However, lesion biopsy revealed ALK-negative cALCL and methicillin-resistant Staphylococcus aureus. A full workup excluded systemic ALCL and, therefore, confirmed the diagnosis of primary cALCL. The patient was placed on methotrexate to treat the lesions and sulfamethoxazole/trimethoprim to treat the infection. Conclusion: Our case highlights the need to consider cALCL in the differential diagnosis of patients with persistent skin lesions.