Extramedullary Plasmacytoma Presenting as a Mediastinal Mass: A Comment

Selami K. Toprak, Sema Karakus, Pervin Topcuoglu
2012 Turkish Journal of Hematology  
We read with great interest the recent publication about extramedullary plasmacytoma (EMP) by Shukla et al., in which they concluded that plasmacytoma involving the mediastinum is an early indication of the diagnosis of occult multiple myeloma (MM), which should be included in the differential diagnosis of mediastinal masses [1]. About 3%-5% of plasma cell neoplasms may present with isolated extramedullary involvement [2] . Because this disease can be confused with several
more » ... lymphomas-microscopic and immunohistochemical evaluation are essential for accurate diagnosis [3, 4] . We would like to share our experience concerning the refractory course of EMP. A 62-year-old male presented in 2009 with a swollen left-anterior cervical lesion. MRI showed lytic lesions on several bony elements (suggestive of MM) and a plasmacytoma-like appearance of the swollen region. The patient's medical history was positive for similar swelling of the same region in 2000. The lesion was totally excised and diagnosed as EMP. Subsequently, the patient received radiation therapy (XRT) and the lesion remained silent for the following years. In 2009 he was diagnosed as stage II MM, subsequently given systemic chemotherapy, and had a very good partial response. The lesion persisted, decreasing in size by only 10%. Although the patient's medical history and MRI findings were suggestive of the diagnosis, biopsy samples were histopathologically assessed to better establish the final status of the lesion, and showed fibrotic tissue remnants. The patient underwent autologous hematopoietic stem cell transplantation (AHSCT) using high-dose melphalan. Urine immunofixation electrophoresis was positive during the front-line chemotherapy, but was negative post AHSCT. The treatment was considered successful in terms of MM response, but the lesion (thought to be a plasmacytoma) persisted, at 30% of its original size. Our opinion-and that of several surgeons-was that any surgical intervention could lead to major life-threatening complications; therefore, routine outpatient follow-up provided. MRI is a useful tool for evaluating the extent and size of EMP lesions; however, the role of MRI in staging EMP is not clear. Diagnosis of EMP is based on immunohistochemistry and the exclusion of a systemic plasma-cell proliferative disorder [5] . In the presented case, although not proven histopathologically, relapse and subsequent progression to MM, as is expected in 30% of cases, occurred 9 years after the initial diagnosis. Interestingly, front-line high-dose chemotherapy resulted in an excellent MM response, similar success rates could not be obtained in terms of lesion size, which persisted with a lower than 50% decrease. As EMPs are highly radiosensitive tumors, XRT alone is considered the treatment of choice, with local control rates of 80%-100% [5] . Yet, this treatment modal-
doi:10.5505/tjh.2012.24382 fatcat:fyuhamofp5fghdnv67ybkbrq6q