Patients with immunodeficiency, whether congenital or acquired, have a significantly higher incidence of malignancies, especially mature lymphoid neoplasms and lymphoproliferative disorders. We present the case of a 50-year-old patient with a history of dermatomyositis and antisynthetase syndrome on immunosuppressive therapy, who consulted due to increased volume of the lacrimal gland in the upper left eyelid, associated with weight loss and night sweats. He was admitted for an elective biopsy. The day after the postoperative period, she evolved with an acute abdomen. Computed axial tomography revealed multiple hypodense lesions in the liver, spleen, kidneys, and adrenal glands associated with a perforated tumor in the transverse colon and free fluid in the peritoneal cavity. In this scenario, an infectious, neoplastic, or rheumatological etiology was considered a differential diagnosis, especially in the context of our patient. Finally, the biopsies evidenced extensive necrosis with angiocentric and angiodestructive lymphoid infiltration associated with positive EBV. After extensively reviewing the symptoms, histology, and new classifications of mature B-lymphoid neoplasms, the diagnosis of polymorphic B-lymphoproliferative disorder, lymphomatoid granulomatosis-type was made, an uncommon entity rarely associated with iatrogenic immunosuppression.