Pseudo liposarcomatous plasma cells in a patient with liposarcoma and lymphoplasmacytic lymphoma.

First, patients may always develop a second severe illness, even a second cancer. Second, things are not always as they are expected to be. So, careful diagnosis is mandatory. Third, morphology is very important, but sometimes misleading. Always be aware of morphological variants!

A bone marrow examination was performed in a 60‐year‐old patient who suffered from B symptoms and generalized lymphadenopathy. A previous axillary lymph node excision revealed an indolent B‐cell lymphoma with coexpression of CD5 and CD23. Some weeks before, on left arm, a myxoid liposarcoma grade 2 was resected (Figs. 1 and 2) with no further tumor manifestations. Adjuvant irradiation was implemented. As another meaningful analysis, IgM kappa paraproteinemia was detected at moderate level (19.3 g/L). Bone marrow examination was performed showing marked hypercellularity due to an impressive infiltration of small mature lymphocytes with often plasmacytoid forms (about 85%) with 13% plasma cells. From morphological aspect, suspicion of a lymphoplasmacytic lymphoma (LPL) raised. Surprisingly, some of the plasma cells had a so‐called pseudoliposarcomatous morphology (Fig. 3) 1. On biopsy section, these results were confirmed without having immunohistochemically evidence for liposarcoma spread in the bone marrow and positive CD138 staining of these peculiar cells (Fig. 4). Despite confirmed immunophenotype mentioned above and complex karyotype aberrations (including most frequently in SLL‐detected del[11q]) in seven of 11 metaphases, morphology and p.L265P‐mutation in exon 5 of MYD88 together with moderate IgM paraproteinemia led to the final diagnosis of macroglobulinemia Waldenström. The same MYD88 mutation could afterwards be detected in originally excised axillary lymph node. Around 5% of LPL are considered to be CD5 positive 2, and about 80%–90% are harboring an MYD88 mutation (which is very rare in small lymphocytic lymphoma) 3. So in our patient, after completion of radiotherapy, an immunochemotherapy with rituximab and bendamustine was successfully initiated. In conclusion, we commemorate the rare morphological variant of pseudoliposarcomatous plasma cells, which should not be confounded with liposarcoma occurring at unusual sites or metastatic. Because of known precedent liposarcoma in our patient, further examinations such as immunohistochemistry, immunophenotyping, and molecular diagnostics helped to set the proper diagnosis.

Figure 1

Initial diagnosis of liposarcoma.

Figure 2

Initial diagnosis of liposarcoma (aggrandized).

Figure 3

Pseudoliposarcomatous plasma cells in bone marrow cytology.

Figure 4

CD138 staining for plasma cells in bone marrow trephine biopsy.

Authorship

Adrian Schmidt: wrote the manuscript and involved in diagnostic process. Antoinette Monn: involved in diagnostic process and responsible for pictures. Elisabeth Schmidt‐Weiss: wrote the manuscript. Mathias Schmid: involved in diagnostic process. Beatrix Boesch: involved in diagnostic process and responsible for pictures.

Conflict of Interest

None declared.