Imprint cytology of low-grade B-cell lymphoma of mucosa-associated lymphoid tissue arising in the thymus: a case report

Mucosa-associated lymphoid tissue lymphoma of the thymus associated with Sjögren's syndrome: report of a case

A 68-year-old Japanese man with Sjögren's syndrome was pointed out to have a nodular shadow in the anterior mediastinum. The tumor was resected under video-assisted thoracoscopy and it was pathologically diagnosed to be thymic mucosa-associated lymphoid tissue (MALT) lymphoma. There has been no recurrence for 17 months after surgery. Mucosa-associated lymphoid tissue lymphoma of the thymus is rare, and its pathological diagnosis requires sufficient knowledge and experience. Since thymic MALT lymphoma is distinct from MALT lymphoma of other sites in several ways, including gene abnormalities and geographic distribution, an alternative oncogenic pathway and the influence of racial and/or environmental factors must be considered to be involved. However, since the number of reported thymic MALT lymphomas is limited, these issues are still unclear. The accumulation of further similar cases will help to elucidate various issues concerning thymic MALT lymphoma associated with Sjögren's syndrome.

Thymic and pulmonary mucosa-associated lymphoid tissue lymphomas in a patient with Sjögren’s syndrome and literature review

Mucosa-associated lymphoid tissue lymphoma (MALToma) has been reported in several organs. Among MALTomas, thymic and pulmonary MALTomas are rare. The present report describes a patient with Sjögren's syndrome who presented thymic and pulmonary MALTomas. Although the exact pathogenetic relationship between these two tumours is uncertain, it is likely that the underlying immune dysregulation related to Sjögren's syndrome contributed to the occurrence and the unusual manifestation of MALTomas in this patient.

Mucosa-associated lymphoid tissue lymphoma of the thymus: a case report with no evidence of MALT1 rearrangement

We report a case of thymic mucosa-associated lymphoid tissue (MALT) lymphoma (TML) that presented as an asymptomatic mediastinal mass in a 40-year-old woman with a past history of Sjögren syndrome. This case had the characteristic clinical and pathological features of TML, as found in most of the 24 previously reported cases, i.e., autoimmune context, especially Sjögren syndrome, IgA secretion, large epithelial cysts, lymphoepithelial lesions involving residual Hassal's corpuscles, epithelial cysts, and a marked plasmacytic differentiation with IgA expression. Reverse-transcription polymerase chain reaction for t(11;18)(q21;q21) was negative, in agreement with recently published data. In this case, investigation for t(14;18)(q32;q21) using fluorescent in situ hybridization was also performed and supplied negative results. Neoplastic cells were negative for MAL, a marker of primary mediastinal large B cell lymphoma (PMBL). Altogether, these findings further support that among MALT lymphomas, TML have peculiar clinical and morphological characteristics and appear not to involve MALT1 rearrangement. They also suggest the absence of a relationship between TML and PMBL.

Marginal zone and mantle cell lymphomas: assessment of cytomorphology in subtyping small B-cell lymphomas

The diagnosis of malignant lymphomas by fine-needle aspiration biopsy (FNAB) is increasing in utilization. The cytomorphologic distinction among the small B-cell lymphomas may be quite difficult. We are unaware of anyone who has compared directly mantle cell lymphoma (MCL) and marginal zone lymphoma (MZL) in FNAB. Our major goal was to examine the cytomorphologic attributes of MCL and MZL and to look for features distinctive of or suggestive of either neoplasm. Seven immunophenotypic MCL and seven immunophenotypic MZL aspirates were evaluated for a number of cytomorphologic features in direct smears. Features favoring MCL include a relatively monomorphic cellular population, prominent nuclear membrane contour irregularities, and mitotic figures. Conversely, a polymorphic cellular population suggested MZL. However, due to extensive overlap of specific cytologic features, the two lymphomas cannot be definitively distinguished based solely on cytomorphology. Although there are cytomorphologic attributes suggestive of either MCL or MZL, considerable overlap exists. Based on an individual case basis, the distinction cannot be made reliably by morphology alone; ancillary studies, e.g., immunophenotyping, are essential.

Fine-needle aspiration biopsy findings in marginal zone B cell lymphoma

Marginal zone B cell lymphomas (MZBCLs) represent a category of non-Hodgkin's lymphoma which may arise in a wide variety of extranodal organs where they are termed low grade B cell lymphomas of mucosa-associated lymphoid tissue (MALT). MZBCLs may involve primarily lymph nodes and or spleen where they are designated monocytoid B cell lymphoma or splenic marginal zone lymphoma, respectively. Recognition of this category of lymphoma, in particular, extranodal MALT lymphoma, is clinically significant in determining optimal therapy. Although there have been recent case reports describing the cytologic findings in low grade MALT lymphoma in various extranodal organs, this category of lymphoma has not been widely recognized or discussed in the cytology literature. The cytologic findings in seven fine-needle aspirations and two bronchial washings of histologically confirmed marginal zone lymphoma (five extranodal MALT lymphomas and four nodal marginal zone lymphomas) are described. In all of the cases, the cytologic specimens showed a polymorphous proliferation comprising a predominant population of intermediate sized lymphoid cells with centrocyte-like or monocytoid features, transformed cells, and variable numbers of plasma cells. These findings, while highly suggestive of MALT lymphoma in extranodal proliferations, may be more difficult to distinguish from reactive conditions in lymph nodes.

Gastric low-grade mucosa-associated lymphoid tissue lymphomas: their histogenesis and high-grade transformation

Gastric low-grade mucosa-associated lymphoid tissue (MALT) lymphoma is a unique disease. A vast majority of lymphoma cells are centrocyte-like cells or resemble monocytoid B cells, and occasionally show plasmacytic differentiation. Immunophenotypical and immunogenotypical examinations have indicated that they are in the differentiation stage of memory B cells, whose normal counterparts are marginal zone lymphocytes or monocytoid B cells in the lymphoid tissues. It arises from chronic gastritis closely associated with Helicobacter pylori (H. pylori) infection. Mucosa-associated lymphoid tissue lymphomas of other organs are also based on acquired MALT associated with chronic inflammation or autoimmune diseases. Interestingly, the majority of gastric low-grade MALT lymphomas regress by the eradication of H. pylori. The lymphoma cells, however, are not derived from B cells reacting with H. pylori itself but from autoreactive B cells. Although the mechanism of their oncogenesis has not been clarified, previous data suggest that autoreactive B cells proliferate in response to H. pylori-specific T cells, presumably with some cytokines. The genetic instability of such B cells then induces chromosomal abnormalities including trisomy 3 and/or other genetic changes. These B cells have the ability of autonomic proliferation and, even so, they might be sensitive to T cell stimuli. Low-grade gastric lymphomas occasionally progress to high-grade malignancy. The high-grade component of MALT lymphomas are composed of large-sized lymphoma cells that are morphologically indistinguishable from nodal large B cell lymphomas. This high-grade transformation is associated with p53 abnormalities or Bcl-6 overexpression. Gastric MALT lymphoma may provide a useful model in understanding multistep lymphomagenesis.

Low-grade lymphoma of mucosa-associated tissue in the parotid gland: a case report of fine-needle aspiration cytology diagnosis using flow cytometric immunophenotyping

A 66-year-old woman with Sjögren's syndrome for 7 years presented with an enlarged right parotid gland. The left parotid gland, which showed myoepithelial sialadenitis (MESA), had been resected 4 years earlier. A fine-needle aspiration (FNA) biopsy of the right parotid gland was performed. Examination of the smears revealed cells of intermediate size with a round-to-irregular nuclear outline and distinct pale cytoplasm intermixed with small mature round lymphocytes. The chromatin was slightly paler and less clumped than in small mature lymphocytes. A small inconspicuous nucleolus was seen in most of the cells. Flow cytometry immunophenotyping performed on the FNA biopsy material showed a monoclonal population of B cells with kappa light chain restriction. The cytomorphology coupled with the immunophenotyping study in this clinical context suggested the diagnosis of low-grade B-cell lymphoma of mucosa-associated lymphoid tissue (MALT). Extensive staging work-up revealed no evidence of disseminated disease. The right parotid gland was surgically excised. Histology and gene rearrangement studies confirmed the cytologic diagnosis. To our knowledge, this is the first description of a low-grade lymphoma of MALT in a salivary gland to be diagnosed by FNA.