Dados do Trabalho

Título

Mediastinal extramedullary plasmacytoma – rare imaging finding in multiple myeloma

Introdução

Extramedullary plasmacytoma are neoplastic proliferation of plasma cells that arises from
organs or tissues and rarely involves the mediastinum. Our case highlights that although uncommon, extramedullary plasmacytoma should be included in the differential diagnosis of mediastinal masses.

Descrição

An 54 year-old woman was referred to our emergency department in April 2022 with hyporexia, asthenia, weight loss and right subcostal pain. She had been diagnosed with IgG-Kappa subtype multiple myeloma (MM) three years ago. At the time of the MM diagnosis she had multiple lytic bone lesions, anemia, elevated monoclonal and protein serum levels. The bone marrow biopsy revealed more than 56% of plasma cells.
She underwent 6 cycles of chemotherapy and posteriorly she was submitted to autologous stem cell transplantation and had thalidomide for maintenance. Investigation of the new symptoms included a chest and abdominal computed tomography.
Percutaneous ultrasound-guided biopsy of the mediastinal mass was performed. Histopathological examination showed plasma cell infiltration of the pleura and the immunohistochemical staining demonstrated tumor cells positive for kappa light chain and CD138.
Treatment for the relapsed MM consisted of radiation therapy of the mediastinal mass. Daratumumab, bortezomib and dexamethasone were also prescribed. The 2 months follow-up chest CT scan showed successful response to radiotherapy with significant decrease in tumor size.

Discussão

Multiple myeloma (MM) it is the second most common hematologic malignancy and the most frequent skeletal cancer, when metastatic bone lesions are not taken into consideration.
Extramedullary plasmacytoma (EMP) is defined as clonal plasma cells growth at anatomic sites distant from the bone marrow. Incidence of EMP range from 7% to 17% at diagnosis and from 6% to 20% during the course of MM.
EMP can occur at any site, but almost 90% develop in the head and neck area, with a predilection for the upper respiratory tract and oral cavity.
Rare sites of involvement include: gastrointestinal tract, liver, spleen, pancreas, and other organs and it is very unusual in the mediastinum. The occurrence of EMP has been associated with a poorer MM prognosis.
Intrathoracic EMP imaging findings can mimic multiple pathologies, such as primary carcinoma, sarcoma, neuroendocrine tumors and lymphoma.

Palavras Chave

Plasmacytoma; multiple myeloma; mediastinal mass; neoplasm; diagnosis