Primary Extranodal NK/T-Cell Lymphoma Presenting as Neurolymphomatosis Involving Multiple Cranial Nerves: A Case Report.

Neurolymphomatosis (NL) is a rare condition caused by the lymphomatous or leukemic infiltration of nerves and manifests as neuropathy. Most often, NL is associated with B-lineage non-Hodgkin lymphoma (NHL) and only infrequently occurs in conjunction with T- or NK-lineage NHL. Extranodal NK/T-cell lymphoma (ENKTL)-associated NL is exceedingly unusual, with only 9 cases described in the English language literature, in addition to our case. Diagnosis of NL is challenging, as the entity can mimic neuropathies of more common etiologies, and an adequate biopsy may be difficult to obtain. Timely diagnosis demands a high index of suspicion, especially for patients without a history of hematologic malignancy. We expand upon a unique case of NL exclusively involving cranial nerves and cauda equina nerve roots, as the initial manifestation of ENKTL, and contextualize our findings within the framework of previously reported NK/T-lineage NL cases.

Deletion of Tet2 in mice leads to dysregulated hematopoietic stem cells and subsequent development of myeloid malignancies.

TET2 is mutated/deleted with high frequencies in multiple forms of myeloid malignancies including MDS, CMML, MPN, and AML. However, little is known regarding the biological function of TET2 and its role in the pathogenesis of myeloid malignancies. To study the function of TET2 in vivo, we generated a Tet2 knock out mouse model. Deletion of Tet2 in mice led to dramatic reduction in the 5-hydroxymethylcytosine levels and concomitant increase in the 5-methylcytosine levels in the genomic DNA of BM cells. The Tet2(-/-) mice contained an increased Lin(-)Sca-1(+)c-Kit(+) (LSK) cell pool before the development of myeloid malignancies. A competitive reconstitution assay revealed that Tet2(-/-) LSK cells had an increased hematopoietic repopulating capacity with an altered cell differentiation skewing toward monocytic/granulocytic lineages. Approximately 1/3 of Tet2(-/-) and 8% of Tet2(+/-) mice died within 1 year of age because of the development of myeloid malignancies resembling characteristics of CMML, MPD-like myeloid leukemia, and MDS. Furthermore, transplantation of Tet2(-/-), but not wild-type (WT) or Tet2(+/-) BM cells, led to increased WBC counts, monocytosis, and splenomegaly in WT recipient mice. These data indicate that Tet2-deficient mice recapitulate patients with myeloid malignancies, implying that Tet2 functions as a tumor suppressor to maintain hematopoietic cell homeostasis.

Brentuximab vedotin as a bridge to combination chemotherapy in gray zone lymphoma with severe liver impairment: a case report.

Background: Gray zone lymphoma (GZL) is a rare lymphoma subtype characterized by features intermediate between diffuse large B-cell lymphoma (DLBCL) and classic Hodgkin lymphoma (cHL). The optimal first-line treatment for GZL remains undefined, particularly for patients with poor performance status or baseline organ impairment. Brentuximab vedotin (BV), a targeted therapy that binds to CD30, a TNFR superfamily member involved in NF-kB signaling, has shown promise in the treatment of CD30-positive lymphomas. However, its use in GZL, especially in patients with severe liver impairment, has not been reported previously. Case description: We present a case of a 37-year-old male with GZL and severe liver impairment at initial presentation. The patient initially received monotherapy with BV, which resulted in a marked improvement in liver enzymes and bilirubin levels. Subsequently, combination cytotoxic chemotherapy consisting of dose-adjusted etoposide, prednisone, cyclophosphamide, and doxorubicin (DA-EP_CH) was added. Repeat imaging revealed near complete resolution of lymphadenopathy and significant reduction in hepatosplenomegaly. The patient completed a full course of chemotherapy and achieved a complete response. Follow-up examinations showed no evidence of recurrent disease, and the patient resumed full-time work. Discussion: GZL poses diagnostic challenges due to its overlapping features with DLBCL and cHL. Accurate diagnosis relies on comprehensive histopathological evaluation, immunophenotyping, and molecular analysis. The optimal first-line treatment for GZL remains uncertain. BV shows promise as an addition to chemotherapy in GZL, even in the presence of severe liver impairment. The molecular pathogenesis of GZL is complex and heterogeneous, frequently involving aberrant NF-kB signaling and impaired apoptosis regulation via loss of TP53 expression. Understanding the underlying molecular mechanisms is essential for developing targeted therapies and identifying predictive biomarkers for treatment response. Conclusion: This case demonstrates the successful use of BV as a bridge to cytotoxic chemotherapy in a GZL patient with severe liver impairment, highlighting its potential safety and efficacy even in the setting of end-organ failure. Further investigation is warranted to define optimal treatment strategies, identify predictive biomarkers, and improve outcomes for patients with this rare and challenging lymphoma subtype.

A Rare Presentation of HIV-Negative Plasmablastic Lymphoma: A Diagnostic Dilemma.

Plasmablastic lymphoma (PBL) and plasmablastic plasma cell myeloma (PCM) have many overlapping characteristics. Clinical correlation can help make the distinction between the two entities. Human immunodeficiency virus- (HIV-) negative PBL is a rare disease, making the diagnosis more challenging. While there is no standard of care for PBL, current recommendations include dose-adjusted EPOCH (etoposide, vincristine, doxorubicin, cyclophosphamide, and prednisone), with or without bortezomib. We report an aggressive case of HIV-negative plasmablastic lymphoma and discuss the challenge in establishing a diagnosis. We review the literature regarding this disease and current recommendations for treatment.

Nocardia farcinica isolated from bronchoalveolar lavage fluid of a child with cystic fibrosis.

Nocardia spp. can cause pulmonary infection, usually in the setting of immunosuppression or underlying lung disease. There have been a few reports of these organisms isolated from cystic fibrosis patients and, when recovered, the isolates were almost always Nocardia asteroides. We present the first reported case of a child with cystic fibrosis harboring Nocardia farcinica.