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Case 11

Clinical and haematological data
This 60-yr-old man was admitted to hospital because of thoracic pain and presented with a right-sided thoracic mass involving soft tissues and one rib. No hepato-splenomegaly, no adenopathy. No other skeletal lesion. Hb 111 g / l, L 4.9 G / l, T 29 G /l. No paraprotein, no Bence Jones protein.

BM biopsy : Shows a diffuse and massive infiltration by medium - to large sized cells presenting pleomorphic and often eccentric nuclei, fine chromatin, nucleoli, and moderately abundant cytoplasm. Increase in reticulin.
At IHC examination, the cells are negative for all tested markers (epithelial, lymphoid, melanoma, Ewing, Ig, CD30…), except for CD138 /Syndecan-1
A needle biopsy of the thoracic mass yielded the same morphological and IHC results

Interpretation and diagnosis : Multiple Myeloma, non - secretory, expressing CD138

BM aspirate contained some atypical cells, so that flow cytometry was performed and confirmed the diagnosis. The tumour cells coexpressed CD38 and CD138. No sIg could be detected. CIg were tested : IgA expression could be found; but no light chain was detected.

Comments
The role of BMB and IHC in the diagnosis of MM is well illustrated by this cases of non secretory MM, exhibiting very atypical morphology. According to the literature and our own experience, the monoclonal Ab CD138 is very helpful in characterising the plasma cells and selectively differentiating malignant plasma cells from other malignancies (immunoblastic lymphoma, poorly differentiated carcinoma). Note that in a proportion of MM cases expression of CD45 and/or B-cell associated antigens and, occasionally, aberrant expression of CD45RO (UCHL-1) or CD30 or non-haematopoietic antigens (EMA, vimentin) represent diagnostic pitfalls.

Syndecan-1 (CD138) is a transmembrane heparin sulphate proteoglycan expressed in different stages of differentiation of normal lymphoid cells, i.e. in pre-B-cells and Ig producing plasma cell. Its normal function or presence in lymphoid malignancies is largely unknown. According to Chilosi et al (1999), CD138/Syndecan -1 is a useful immunohistochemical marker of normal and neoplastic plasma cells. On routine trephine bone marrow biopsies (paraffin embedded and decalcified) virtually all normal and neoplastic plasma cells express clear-cut membrane CD138 immunostaining.

Case 11. Multiple Myeloma.

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