AIHA is caused by immune dysregulation leading to the production of autoantibodies, which in turn accelerate the destruction of red blood cells (hemolysis). This exceeds the compensatory capacity of the bone marrow and ultimately leads to anemia (5). AIHA can be primary or secondary; and approximately 50% of secondary AIHA cases are associated with autoimmune diseases or lymphoproliferative disorders (6). Among these, chronic lymphocytic leukemia (CLL) is most frequently associated with AIHA, whereas the link with other lymphoma subtypes has been less commonly reported (7).The pathophysiological mechanisms of lymphoma-associated AIHA remain incompletely understood. Studies in CLL have suggested that immune disorders (including both humoral and cellular immune abnormalities), unmutated IGHV status, specific IGHV frameworks, and adverse cytogenetic lesions (such as del(17p) and/or del(11q)) are risk factors for AIHA (8). Thieblemont et al. (9) retrospectively analyzed 81 patients with SMZL and found that 16 cases experienced autoimmune events (10 cases of AIHA, 4 cases of immune thrombocytopenia, and 2 cases of acquired coagulation disorders). Other studies have suggested that such autoimmune events may be manifestations of the active stage of SMZL (10). Among the reported cases of MZL complicated by AIHA, some patients were diagnosed with MZL shortly after the onset of AIHA, some developed AIHA after an established lymphoma diagnosis, and others were diagnosed with MZL several years after the initial AIHA episode. Overall, when lymphoma, especially aggressive subtypes, is complicated by AIHA, the clinical course is often severe and may present with severe or even life-threatening anemia. Refractory AIHA is also common in this setting. These patients often respond poorly to standard immunosuppressive therapy, and corticosteroid use may mask lymphoma-related manifestations, contributing to diagnostic delay. Therefore, AIHA patients with concomitant hepatosplenomegaly, lymphadenopathy, or recent unintentional weight loss should be promptly evaluated for underlying lymphoma. Currently, AIHA is considered both a potential adverse prognostic factor and a marker of disease activity in SMZL (11).

In our patient, lymphocytosis and splenomegaly were already evident at the initial rheumatology visit for gout, but no further hematologic work-up was undertaken. Eight months later, severe warm AIHA with profound anemia and jaundice was the main reason for admission. If management had focused solely on “primary AIHA,” the lymphoma might have remained undiagnosed. Instead, the combination of AIHA, massive splenomegaly and lymphocytosis prompted bone marrow evaluation, which revealed a clonal small B-cell lymphoma. The rapid normalization of hemoglobin and bilirubin after the first cycle of R-CVP underscores that effective control of the underlying lymphoma is crucial for resolving lymphoma-associated AIHA. This case highlights the importance of evaluating AIHA patients with splenomegaly, lymphocytosis, or other “red flags” for an underlying small B-cell lymphoma. Conversely, it also underscores that autoimmune cytopenias may serve as a marker of disease activity in SMZL.

Notably, this patient had a long history of chronic gouty arthritis before the diagnosis of lymphoma, suggesting a potential pathogenetic link rather than simple coexistence. Numerous studies have demonstrated that patients with autoimmune diseases such as rheumatoid arthritis have a significantly increased risk of non-Hodgkin lymphoma (12). This risk appears to correlate with disease activity and cumulative inflammatory burden. Together, these findings support the hypothesis that chronic inflammation can drive B-cell clonal expansion and lymphomagenesis. Although gouty arthritis is not a classic autoimmune arthritis, monosodium urate crystals can activate the NLRP3 inflammasome and drive IL-1β mediated inflammation (13). The resulting chronic, low-grade inflammatory milieu may favor lymphomagenesis, although a direct causal link between gout and lymphoma has not been established. Therefore, the pre-existing gouty arthritis in this case may have provided, at least in part, a permissive background for abnormal B-cell clonal proliferation and subsequent evolution. This raises the possibility that the sequential occurrence of these two conditions may not be entirely coincidental.

The MYD88 L265P mutation is a common somatic point mutation in the MYD88 gene (myeloid differentiation primary response 88; c.794T>C), leading to substitution of leucine by proline at codon 265 (p. Leu265Pro). This mutation constitutively activates NF-κB and JAK/STAT signaling, promoting B-cell proliferation and survival, and contributing to lymphomagenesis (14, 15). It is detected in > 90% of patients with lymphoplasmacytic lymphoma/Waldenström macroglobulinemia (LPL/WM) and is closely associated with IgM monoclonal gammopathy and plasmacytic differentiation (14, 16). In contrast, it is found only in a minority of SMZL cases, and is rarely seen in other marginal zone lymphoma subtypes, which may complicate differential diagnosis when present (14, 17–20). In a retrospective study, Azahara et al. (21) used TaqMan allele-specific PCR to assess 114 MZL patients (7 nodal MZL, 21 MALT lymphomas, and 86 SMZL) and 24 LPL patients. The MYD88 L265P mutation was detected in 15% of SMZL cases (13/86) and in 79% of LPL cases (19/24), but was absent in nodal MZL and MALT lymphoma. Compared with MYD88 wild-type cases, patients harboring the mutation were more likely to have an IgM monoclonal gammopathy (70% vs. 18%) and higher IgM levels (3.0–11.9 g/L vs. 3.7–6.6 g/L), whereas age, hemoglobin, LDH, β2-microglobulin, serum albumin, and prior hepatitis B virus infection did not differ significantly. Histologically, SMZL cases with MYD88 L265P mutation more frequently exhibited plasmacytic differentiation (9/13, 69%).

In our case, bone marrow smears showed 39.5% mature small lymphocytes, some with cytoplasmic (villous) projections, in keeping with previously described cytologic features of SMZL (22). Bone marrow biopsy revealed nodular and interstitial infiltrates of small B-cells expressing CD20 and CD79a but negative for CD3, CD5, CD10 and CyclinD1, which supporting a diagnosis within the spectrum of MZL (23). Notably, the Ki-67 index of about 40% was higher than usually reported in classical indolent SMZL and suggests a more proliferative clone. Whole-body PET-CT showed diffuse, moderately increased FDG uptake in the spleen (SUVmax ~4.8). Previous studies have shown that the SUVmax of aggressive or transformed lymphomas is generally higher than that of indolent lymphomas. However, there is substantial overlap in SUV ranges between these entities, and a single SUV threshold cannot reliably distinguish indolent from aggressive disease (24). Targeted NGS detected the MYD88 L265P mutation with a variant allele frequency of 22.4%, indicating a sizable clonal population. However, the patient had no IgM paraproteinemia or hyperviscosity, no cold agglutinin disease or cryoglobulinemia, and no peripheral or central nervous system involvement. Bone marrow morphology did not show typical lymphoplasmacytic differentiation, and CD138 and Mum-1 were only focally positive. Taken together, these findings effectively excluded LPL/WM and favored classification as a small B-cell lymphoma highly suspicious for SMZL. From an immunologic perspective, MYD88-driven signaling may help sustain both lymphoma cell survival (14) and a pro-inflammatory cytokine milieu that favors autoantibody production, potentially contributing to autoimmune cytopenias (25) such as AIHA. However, this hypothesis still requires validation.

Copy number alterations and complex karyotypes are key features of many B-cell neoplasms. In MZL, trisomies of chromosomes 3 and 18 and mutations in chromatin-remodeling genes are relatively common (26). Salido et al. (27) analyzed karyotypes from 330 SMZL patients and found that 53% had complex karyotypes (≥3 abnormalities), with frequent lesions involving gains of 3/3q and 12q, deletions of 7q and 6q, and translocations affecting 8q/1q/14q. Among these, 7q deletion (14–44%) and 3q gains (20–30%) are particularly characteristic of SMZL. Our patient’s karyotype showed multiple structural and numerical abnormalities, including 8q deletion, 14q deletion and trisomy 18. FISH did not detect a classic MYC-IGH fusion, but MYC copy number gain was observed in approximately 10% of nuclei. NGS confirmed gains in 8q24.11-q24.21 encompassing the MYC locus, along with gains of chromosome 18. In addition, NGS revealed cryptic abnormalities not captured by conventional karyotyping or locus-specific FISH, including 3q gains, 16p deletions, and copy-neutral loss of heterozygosity on 17q. Among these, gains of 3q and trisomy 18 are recurrent abnormalities in SMZL, while 17q may suggest potential deregulation of the TP53 pathway. Importantly, this case exhibited MYC copy number gain.

MYC is a multifunctional transcription factor that promotes tumorigenesis by enhancing cell proliferation, stimulating angiogenesis, and increasing genomic instability (28). In lymphomas, MYC abnormalities predominantly manifest as gene rearrangements and amplifications, whereas point mutations are relatively rare. It is crucial to distinguish MYC copy number gain/amplification from MYC rearrangement, as their biological and prognostic implications may differ and remain incompletely defined. In DLBCL, MYC amplification has been associated with adverse prognosis (29). In mantle cell lymphoma, MYC overexpression is an independent predictor of poor outcome, and both amplification and translocation events involving MYC may contribute to disease progression (30). Although MYC abnormalities are exceedingly rare in MZL, studies of MZL undergoing histologic transformation to DLBCL have shown marked upregulation of MYC protein. Even in the absence of detectable MYC rearrangement, this upregulation can contribute to disease progression and aggressive transformation (31). Therefore, MYC alterations are often regarded as a “molecular warning signal” of progression or impending transformation. Rearrangements often suggest highly aggressive disease. Even copy-number gains may signal clonal evolution and justify close surveillance for increasing disease burden, a higher Ki-67 index, or morphologic transformation (e.g. to DLBCL or Burkitt-like lymphoma).

Although a classic MYC translocation was not identified in this patient, the presence of MYC amplification together with 3q gains, trisomy 18 and other copy number aberrations indicates considerable genomic complexity and potential adverse biological behavior. Clinically, this patient should therefore be considered part of a high-risk subset of SMZL-like lymphomas with a non-negligible risk of histologic transformation, warranting closer follow-up and periodic re-evaluation.

The major limitation in this case is the absence of splenic histopathology, which represents the gold standard for diagnosis and grading of SMZL. Our conclusions rely on an integrated assessment of bone marrow histology, immunohistochemistry, cytogenetics, molecular findings, and clinical features. Moderately increased splenic FDG uptake (SUVmax ~4.8), a relatively high Ki-67 index (~40%), and MYC copy number gain are uncommon in prototypical indolent SMZL and suggest a degree of biological aggressiveness. Therefore, focal transformation to DLBCL within the spleen cannot be completely excluded. At the same time, the eight-month interval between the initial detection of lymphocytosis and the definitive diagnosis was characterized by relatively slow clinical progression. The patient then achieved complete remission after six cycles of rituximab-based immunochemotherapy, which is consistent with an indolent clinical course. Integrating these observations, we consider the most appropriate designation to be a “small B-cell lymphoma highly suspicious for SMZL with high-risk molecular features,” and explicitly acknowledge the residual diagnostic uncertainty.

This case underscores that, in real-world settings where splenic tissue is not available, multidimensional laboratory tests (including pathology, flow cytometric immunophenotyping, cytogenetics, and NGS) are essential for the precise classification of small B-cell lymphomas and for assessing the risk of histologic transformation. In our patient, five months of post-treatment follow-up have documented a sustained complete remission without recurrent hemolysis, although longer observation is needed to clarify the long-term course. Once signals of “disease progression” are observed, the treatment should be promptly adjusted, and targeted pathway drugs (such as BTK inhibitors targeting the MYD88 pathway), clinical trials should be actively considered should be considered for inclusion.