CD3 expression in plasma cell neoplasm (multiple myeloma): A diagnostic pitfall

A metastatic secretory gastric plasmacytoma with aberrantCD3 expression in a dog

“…The expression of the cell surface markers CD79a (a B‐cell receptor signaling component) and CD18 (a leukocyte adhesion molecule subunit) are detected variably in IHC of canine plasma cell neoplasia . Cell membrane staining for CD3, a signaling protein associated with the T‐cell receptor, has been used to identify canine T‐cells for over 20 years and has been documented in aggressive human plasma cell tumors as an exceedingly rare occurrence . Interestingly, a 67‐year‐old human male patient previously diagnosed with MM subsequently developed gastrointestinal bleeding, with clinical investigation revealing the presence of CD3‐positive neoplastic plasma cells within the stomach, however any possible relationship between CD3‐positive plasma cells and gastrointestinal localization would be highly speculative given the rarity of such pathology in both species .…”

“…Cell membrane staining for CD3, a signaling protein associated with the T‐cell receptor, has been used to identify canine T‐cells for over 20 years and has been documented in aggressive human plasma cell tumors as an exceedingly rare occurrence . Interestingly, a 67‐year‐old human male patient previously diagnosed with MM subsequently developed gastrointestinal bleeding, with clinical investigation revealing the presence of CD3‐positive neoplastic plasma cells within the stomach, however any possible relationship between CD3‐positive plasma cells and gastrointestinal localization would be highly speculative given the rarity of such pathology in both species . In a case series classifying lymphoid malignancies in the dog and cat by the WHO system, 2 indolent cases of canine plasmacytoma were reported as positive for both CD3 and CD79a; however, no additional information was given, and diagnosis was based solely on histopathologic morphology .…”

“…12 Interestingly, a 67-year-old human male patient previously diagnosed with MM subsequently developed gastrointestinal bleeding, with clinical investigation revealing the presence of CD3positive neoplastic plasma cells within the stomach, however any possible relationship between CD3-positive plasma cells and gastrointestinal localization would be highly speculative given the rarity of such pathology in both species. 12 In a case series classifying lymphoid malignancies in the dog and cat by the WHO system, 2 indolent cases of canine plasmacytoma were reported as positive for both CD3 and CD79a; however, no additional information was given, and diagnosis was based solely on histopathologic morphology. 13 Understanding the physiologic roles of marker molecules and appreciating the limitations of immunophenotypic markers assisted with the definitive diagnosis of EMP in this case.…”

CD3-positive plasmablastic B-cell neoplasms: a diagnostic pitfall

“…5,6 Aberrant CD3 expression has rarely been described in mature B-cell neoplasms, including diffuse large B-cell lymphoma, classic Hodgkin lymphoma, and follicular lymphoma. 3,[7][8][9][10][11][12][13][14][15][16][17][18]18 CD3 expression in CD20+ B-cell lymphomas is usually not problematic since co-expression of these two markers will prompt further workup with more lineage-specific markers and molecular studies. In another study, we noticed that 6-29% cases of primary effusion lymphoma and its solid variant, HHV8+ large B-cell lymphoma, aberrantly expressed CD3; 19 however, presence of HHV8 infection in the lymphoma cells provides a strong evidence for primary effusion lymphoma in HIV+ patients.…”

Very unusual expression of multiple aberrant T‐cell markers in plasmablastic plasma cell myeloma

“…Additionally, many cases were described as having been initially misinterpreted as peripheral T-cell lymphoma or NK/T-cell lymphoma. [3][4][5] Distinguishing between plasmablastic lymphoma and plasmablastic plasma cell myeloma is difficult, as there is considerable overlap in the expression of common antigens such as F I G U R E 1 A, The initial bone marrow aspirate smear demonstrates "classic" mature plasma cell morphology with mature chromatin, eccentric nucleus, perinuclear halo, and occasional small vacuoles. B, Bone marrow aspirate smear shows neoplastic plasma cells with plasmablastic morphology, large nuclei having round-to-slightly irregular nuclear contours and reticular chromatin, basophilic cytoplasm with occasional small vacuoles, no perinuclear hof, and prominent nucleoli (A,B, Wright-Giemsa, ×1000).…”