CD5-positive marginal zone B-cell lymphoma of the mucosa-associated lymphoid tissue (MALT) of the lung

Abstract

CD5-positive marginal zone B-cell lymphoma of the mucosa-associated lymphoid tissue (MALT) of the lung is very rare. An 82-year-old Japanese woman was found to have an abnormal lung shadow on chest X-ray photography, and was admitted to our hospital. Imaging modalities including X-ray photography, computed tomography, and magnetic resonance imaging showed a small (2×1×1 cm) opacity of the right upper lobe. Transbronchial lung biopsy was performed. It showed severe proliferation of small lymphocytes. The small lymphocytes were centrocytes-like, and minor plasma cell differentiation was recognized. Lymphoepithelial lesions were scattered. Immunohistochemically, the tumor cells were positive for CD5, CD20, CD43, CD45, CD79α, bcl-2, and κ-chain, but negative for CD2, CD3, CD10, CD21, CD23, CD35, CD45RO, CD56, IgA, IgG, IgM, IgD, λ-chain, TdT, and cyclin D1. The Ki-67 labeling was 10%. CD3-positive and CD45RO-positive inflammatory T-cells were scattered in small amount. The pathological diagnosis was CD5-positive marginal zone B-cell lymphoma of the mucosa-associated lymphoid tissue (MALT) of the lung. The patient was treated with chemotherapy (CHOP: cyclophosphamide, hydroxydaunorbicin, vincristine, and predonisone), and the lung tumor disappeared. The patient is now free of the lymphoma 10 years after the first manifestation.

Virtual slides: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1541653085652296.

Figure 1

Histological features. A: Diffuse atypical lymphoid cell proliferation is seen. HE, ×100. B: The atypical cells are small lymphoid cells with hyperchromatic nuclei. Lymphoepithelial lesions are seen. HE, × 400. C: The lymphoepithelial lesions are clearly accentuated by cytokeratin immunostaining. AE1/3 immunostaining, ×200.

Figure 2

Immunohistochemical features. The tumor cells are positive for CD5 (A), CD20 (B), and κ-chain (C). λ-chain was negative (D). A, B, C: ×200. D, x400. The tumor cells were negative for CD3 (E). A small amount of CD3-positive inflammatory cells are seen (E). E: ×200.