Complex Interplay Between Sweet Syndrome and Therapy-Related Myelodysplastic Syndrome After B-Cell Lymphoma Treatment: A Case Report.

BACKGROUND Sweet syndrome (SS), or acute febrile neutrophilic dermatosis, is an inflammatory skin condition often associated with hematologic malignancies such as myelodysplastic syndrome (MDS). Therapy-related MDS (tMDS) is a well-recognized subtype of myelodysplastic syndrome that arises due to exposure to chemotherapy or radiation therapy. Reports on SS in the context of tMDS are limited, with unclear clinical features. CASE REPORT An 86-year-old woman with low-grade B-cell lymphoma, unclassifiable, achieved complete remission following bendamustine-rituximab therapy. She later developed cytomegalovirus viremia, persistent fever, and painful erythematous nodules. Histopathological examination of a skin biopsy confirmed SS. Corticosteroids and colchicine were initiated, leading to resolution of cutaneous symptoms. Despite clinical improvement, she developed progressive pancytopenia. Bone marrow evaluation revealed granulocytic dysplasia, including hypogranulation and pseudo-Pelger-Huët anomalies, with 1.5% ring sideroblasts and 3.2% blasts, consistent with MDS. Azacitidine was administered but proved ineffective in restoring hematopoiesis. The patient died due to an invasive Aspergillus brain abscess. Autopsy findings confirmed the absence of lymphoma recurrence. A literature review identified only 4 previously published cases of SS in tMDS, all of which occurred after the diagnosis of tMDS. CONCLUSIONS This case is notable in that SS preceded the diagnosis of MDS, contrasting with previous reports. Although a direct causal relationship cannot be established, this case underscores the diagnostic complexity of cutaneous and hematologic findings following chemotherapy. Furthermore, the absence of consensus on corticosteroid dosing and duration in immunocompromised hosts highlights the need to carefully balance therapeutic benefits against infection risk in SS associated with hematologic malignancies.