Extramedullary plasmacytoma: cytological and genotypic studies

Abstract

A 62-year-old woman had multiple plasmacytomas in the skin and lymph nodes, without Bence-Jones protein or a monoclonal peak of serum immunoglobulins. Infiltrating plasmacytoid cells expressed cytoplasmic IgG (lambda) and surface CD38, without any B-cell markers. There was no visceral or bone marrow involvement suggestive of multiple myeloma. Southern blot analysis of extracted DNA from the cutaneous lesions showed two rearranged bands with an immunoglobulin, but not a T-cell receptor, gene probe. The patient showed a poor response to chemotherapy, and died of bronchopneumonia. The clinical course and cytological features differentiate multiple cutaneous extramedullary plasmacytomas from solitary cutaneous extramedullary plasmacytoma and cutaneous lesions associated with multiple myeloma.

Multiple primary cutaneous plasmacytomas: Figure 1

“…In situ hybridisation for light chains is useful as there is less variability when compared to immunohistochemistry. Monoclonality was evident in our case; some authors believe that monoclonality is a marker of malignancy 2 – 4. A positive CD138 stain supports plasma cell lineage.…”

“…Twenty-three cases of primary cutaneous plasmacytoma have been reported in the literature, with only six having multiple lesions and clonality 2. This case is an example in which an otherwise healthy patient with multiple cutaneous plasmacytomas continues to be free of systemic disease.…”

“…Multiple myeloma and solitary plasmacytoma involve the bone marrow but can occupy extramedullary sites, including the upper respiratory and gastrointestinal tracts and lymphoreticular organs,2 3 Skin is rarely involved 1 – 5…”

“…Long term follow-up is recommended to ensure appropriate treatment if myeloma develops 1 3 4. Surgical excision is the primary therapy in cases of solitary or few plasmacytomas 2 4 5. Radiotherapy has been used in some patients with varying degrees of success 1 – 3 5.…”

Immunotherapies targeting CD38 in Multiple Myeloma

“…12,14 In contrast, it is absent from the tumor cells of patients with B cell chronic lymphocytic leukemia (CLL), 14 B cell prolymphocytic leukemia (B-PLL), 14 and many patients with Waldenstroem's Disease. 14,22 Importantly, the strongest and most frequent CD38 expression out of all hematologic malignancies was consistently observed on the malignant plasma cells 9 of patients with plasma cell dyscrasias such as monoclonal gammopathy of undetermined significance (MGUS), [23][24][25][26] extramedullary plasmacytoma, 27,28 multiple myeloma, 22,29 plasma cell leukemia, 30,31 and even on myeloma cells within malignant effusions based on MM. 32 In fact, >90% of the malignant plasma cells from patients with MM show surface expression of CD38.…”