When diagnostic clues are hidden in small blood vessels of the skin: Diagnostic challenge in Intravascular Large B-Cell Lymphoma.

Intravascular large B-cell lymphoma (IVLBCL) is a rare extranodal lymphoma characterized by selective growth of neoplastic lymphocytes within small vessels, and often lacking lymphadenopathy or circulating malignant cells. Its clinical heterogeneity and nonspecific symptoms frequently cause delayed diagnosis and treatment. We report 3 new cases in elderly patients presenting with unexplained anemia, systemic symptoms in 2 patients, and purpuric skin lesions in one patient. All were diagnosed via skin biopsy (a purpuric lesion, hemangioma-like lesion and random normal skin, respectively) which revealed intravascular atypical B cells. Two patients developed hemophagocytic syndrome (HPS), aligning with the Asian variant of IVLBCL. One patient had hemangioma-like nodules and lymphadenopathy. These cases highlight the clinical heterogeneity of IVLBCL and emphasize the diagnostic value of skin biopsy in patients with features of HPS (unexplained fever, cytopenia, and elevated lactate dehydrogenase (LDH) or ferritin).