Cytodiagnosis of multiple myeloma presenting as chest wall swellings.

Multiple myeloma is a relatively less common malignant tumor characterized by monoclonal proliferation of plasma cells, affecting primarily the bone marrow and skeletal system.[1] This disease usually presents with bone pain, pathological fracture and anemia, but it can show many modes of presentation such as swelling in the jaw, orbit, rib, sternoclavicular region, scalp, paraspinal region, and tonsil.[2-5] Multiple myeloma presenting primarily as swelling in the chest wall is relatively rare and not many cases have been reported in the literature where fine needle aspiration cytology (FNAC) has helped in making the diagnosis.[14] We present two such cases which were diagnosed initially on cytology and on subsequent work-up confirmed as multiple myeloma.

Case 1

A 65-year-old female presented with a swelling in the anterior chest wall of 6 months duration, which was gradually increasing in size. She also complained of fever and loss of weight. On examination, the swelling measured 6 × 4cm and was non-tender. She had no organomegaly. Her hemoglobin was 8 gm% and the erythrocyte sedimentation rate (ESR) was 110 mm at the end of 1st hour. The chest radiograph showed erosion of the manubrium sterni. FNAC performed on the swelling showed features of plasmacytoma.

Case 2

A 60-year-old male presented with a diffuse swelling of 3 months duration on the anterolateral aspect of the chest wall on the left side. On examination, the swelling was diffuse and measured 12 × 10cm. His hemoglobin was 9 gm% and ESR was elevated to 80 mm at the end of 1st hour. Bence Jones protein was absent in the urine. Skull imaging showed lytic lesions. The swelling was subjected to FNAC.

The aspirated smears from the swellings in the chest wall were stained by hematoxylin and eosin (H and E) and Giemsa stains. The smears in both the cases were cellular and composed of plasmacytoid cells arranged singly and in clusters with varying pleomorphism. Binucleation of the cells was seen.

In the first case, the smears predominantly showed plasmablasts with prominent nucleoli along with few plasma cells showing moderate pleomorphism [Figure 1a]. Plasma cells containing eosinophilic inclusion of immunoglobulin (Mott cells) were also observed in a good number in the smears [Figure 1b].

Figure 1

(a) Smears showing plasmablasts with prominent nucleoli (Giemsa, ×1000); (b) Smear showing Mott cells (Giemsa, ×1000)

The second case on FNAC showed mainly mature-looking plasma cells and cells with nuclear atypia, pleomorphism, binucleation, open chromatin and basophilic cytoplasm [Figure 2a, b]. Abnormal mitotic Figures were also seen.

Figure 2

(a) Smear showing mature looking plasma cells (H and E, ×400); (b) Smear showing plasma cells with pleomorphism. Binucleate forms are seen (H and E, ×400)

The tumors of plasma cells can manifest as multiple myeloma, solitary plasmacytoma and extramedullary plasmacytoma. Multiple myeloma usually presents with low back pain and pathological fracture, but it can show varied presentation such as swelling of the jaw, orbit, and tonsil.[2-5] Swelling on the chest wall is an unusual presentation of multiple myeloma and can be a diagnostic dilemma for the clinicians.[1] In such cases, a cytological diagnosis based on the FNAC of the swellings will definitely be very helpful in guiding the clinician to investigate further for confirmation.

On FNAC, the smears of plasmacytomas are cellular, composed of plasmacytoid cells showing pleomorphism with bi and multinucleation.[4] We found similar appearing cells on the cytology smears of the second case. However, the smears in the first case showed predominantly plasmablasts with prominent nucleoli and eosinophilic intracytoplasmic inclusions with few plasmacytoid cells. In some cases, the cytology smears of myeloma show a mixture of plasmablasts and plasma cells in various stages of maturation with nuclear atypia, moderate pleomorphism and basophilic cytoplasm.[4-6] The first case showed the presence of anaplasia, increased plasmablasts and less number of mature plasma cells, and therefore the cytological evaluation was challenging in comparison to the second case where there were more of mature plasma cells.

In these two cases, a differential diagnosis of chondrosarcoma, primitive neuroectodermal tumor (PNET) (or Askin tumor), and metastatic carcinoma was considered at FNAC. Chondrosarcoma on cytology shows tumor cells with oval nuclei and vacuolated cytoplasm with small pink granules embedded in a pink matrix.[7] PNET is seen in a younger age group and aspirates show a dissociative pattern of small malignant cells having a high nucleus: cytoplasmic (N: C) ratio with fine chromatin and lack nucleoli. The cytoplasmic vacuolation and membranous cytoplasmic blebs are noted occasionally. Metastatic carcinoma was ruled out due to lack of prominent nuclear pleomorphism and any cohesive arrangement of the cells.

In both the cases, the bone marrow aspiration showed more than 30% of plasma cells and urine was positive for Bence Jones protein in one case. The serum protein electrophoresis revealed an “M” spike in both the cases.

Multiple myeloma presenting primarily as a swelling in the chest is quite rare. The presence of increased plasmablasts, anaplasia and unusual location of the tumor are some of the challenges faced during the cytological evaluation. FNAC definitely offers an early and accurate method of diagnosis in such unusual sites of presentation of the disease, and thus is essential in helping the clinicians in clinically unsuspected cases.