Paraneoplastic Autoimmunity Associated with Testicular Myeloid Sarcoma and Chronic Myelomonocytic Leukemia

Myeloid sarcomas are rare extramedullary solid tumors composed of immature myeloid cells. The clinical presentations of these malignant neoplasms are highly variable, ranging from asymptomatic to localized mass effect. Here, we report an unusual case of myeloid sarcoma of the testis found in association with chronic myelomonocytic leukemia where the presenting symptoms were autoimmune pericarditis and migratory arthralgias and myalgias that preceded testicular enlargement by nearly three months. Treatment with both radical orchiectomy and leukemia-directed chemotherapy led to immediate reductions in symptom severity, suggesting that these early symptoms were paraneoplastic in origin. Review of the literature identified the association between hematological malignancies, including chronic myelomonocytic leukemia, and paraneoplastic autoimmune phenomena with features similar to polymyalgia rheumatica and rheumatoid arthritis. Importantly, rheumatologic symptoms related to these disease entities may be easily dismissed as vague or unrelated complaints or treated as purely rheumatologic conditions, thus delaying the formal diagnoses. Clinicians must recognize the common association between possible paraneoplastic rheumatologic symptoms and hematologic malignancies such as chronic myelomonocytic leukemia. 1. Introduction Myeloid sarcomas are tumor masses that consist of myeloid blasts or immature myeloid cells that occur at extramedullary sites throughout the body [1]. While the most commonly affected sites are the skin, lymph nodes, bone, soft tissues, and gastrointestinal tract, these neoplasms may be found at any location and are often accompanied by bone marrow involvement of an underlying hematologic malignancy [2]. Myeloid sarcomas are not associated with a classical presentation but are rather associated with an assortment of clinical findings dependent on tumor size, tumor location, and the direct consequences of underlying hematologic disorders (e.g., infection, bleeding, and organomegaly) [3]. Myeloid sarcomas occur less frequently than many other solid tumors, and the histomorphologic diagnosis is often difficult or delayed in the absence of a previously diagnosed blood-born malignancy [4]. Due to histomorphological similarity to non-Hodgkin’s lymphomas, myeloid sarcomas are often initially confused with aggressive large B-cell lymphomas [5]. Obtaining the correct diagnosis is critical, however, as the chemotherapeutic regimens used for treating malignant lymphoproliferative disorders differ substantially from those used for treating acute