대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Extramedullary plasmacytoma in mediastinum

Radiologic Findings

Fig 1. A chest PA view shows mediastinal widening and bilateral pleural effusions.
Figs 2-5. CT scans reveal a large, enhancing soft tissue mass involving the middle and posterior mediastinum. The mass encases the superior vena cava, right main and lobar pulmonary arteries, and the left main bronchus.
Figs 6-7. Fused PET/CT images show a moderately hypermetabolic lesion (SUVmax 7.4) in the mediastinum.

Brief Review

This case illustrates a rare presentation of a plasmacytoma predominantly involving the mediastinal lymph nodes mimicking a mediastinal lymphoma. It is necessary to exclude plasmacytomas formed in extramedullary locations from bone marrow lesions, as observed in multiple myeloma. More than 80% of tumors occur in the upper respiratory tract, such as the nasopharynx, paranasal sinuses, nasal cavity, oropharynx, and tonsils. In non–upper respiratory tract extramedullary plasmacytomas (EMPs), more than half of the cases are in the gastrointestinal tract and urogenital region, and approximately 10% are in the lungs (including the pleura and bronchi)

An extensive review of the literature identified a limited number of cases with mediastinal involvement by EMPs. Plasmacytomas primarily involving lymph nodes are even rarer. Primary lymph-node plasmacytomas are estimated to represent only 2% of all EMPs. Many primary lymph-node plasmacytomas are mostly described in case-reports, with a minority of cases described as arising in plasma cell-type Castleman’s disease. An EMP in the mediastinum can also present with superior-vena-cava syndrome by its mediastinal location and possibly compressive nature, although deemed rare.
There was a male predominance, and the average age of affected patients was 56 (range: 10–72 years). The most common presentation was neck swelling due to a localized mass. Otherwise, those plasmacytomas were asymptomatic. Immunophenotypically, these lymph node plasmacytomas may have distinct profiles compared with other extramedullary plasmacytomas or myeloma. They have increased CD30 expression and decreased MB2 (B-cell antigen) and CD45RO expression.

References

1. Masood A, Hudhud KH, Hegazi A, Syed G. Mediastinal plasmacytoma with multiple myeloma presenting as a diagnostic dilemma. Cases J 2008;1:116.
2. Miyazaki T, Kohno S, Sakamoto A, Komori K, Sasagawa I, Futagawa S, et al. A rare case of extramedullary plasmacytoma in the mediastinum. Intern Med 1992;31:1363–5.
3. Niwa K, Tanaka T, Mori H, Takahashi M. Extramedullary plasmacytoma of the mediastinum. Jpn J Clin Oncol 1987;17:95–100. 4
4. Menke DM, Horny HP, Griesser H, Tiemann M, Katzmann JA, Kaiserling E, et al. Primary lymph node plasmacytomas (plasmacytic lymphomas). Am J Clin Pathol 2001;115:119–26.
5. Lin BT, Weiss LM. Primary plasmacytoma of lymph nodes. Hum Pathol 1997;28:1083–90.

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