LMO2 expression is frequent in T-lymphoblastic leukemia and correlates with survival, regardless of T-cell stage.

T- lymphoblastic leukemia/lymphoma (T-LL) is an aggressive malignancy of immature T-cells with poor overall survival (OS) and in need of new therapies. LIM-domain only 2 (LMO2) is a critical regulator of hematopoietic cell development that can be overexpressed in T-LL due to chromosomal abnormalities. Deregulated LMO2 expression contributes to T-LL development by inducing block of T-cell differentiation and continuous thymocyte self-renewal. However, LMO2 expression and its biologic significance in T-LL remain largely unknown. We analyzed LMO2 expression in 100 initial and follow-up biopsies of T-LL from 67 patients, including 31 (46%) early precursor T-cell (ETP)-ALL, 26 (39%) cortical and 10 (15%) medullary type. LMO2 expression was present in 50 (74.6%) initial biopsies with an average of 87% positive tumor cells (range 30-100%). LMO2 expression in ETP, medullary and cortical T-LLs was not statistically different. In patients with biopsies after initial therapy, LMO2 expression was stable. LMO2 expression was associated with longer OS (p = 0.048) regardless of T-lymphoblast stage or other clinicopathologic features. These findings indicate that LMO2 is a promising new prognostic marker that could predict patients' outcomes and potentially be targeted for novel chemotherapy, i.e. PARP1/2 inhibitors, which have been shown to enhance chemotherapy sensitivity in LMO2 expressing diffuse large B cell lymphoma (DLBCL) tumors by decreasing DNA repair efficiency.

Ocular Adnexal MALT Lymphoma in Association With Rosai-Dorfman Disease in a Child.

A 12-year-old boy presented with persistent proptosis and periorbital swelling after a school altercation. MRI revealed a mass in the right superonasal orbit extending along the orbital roof to the frontal bone and right frontal sinus, and intracranially to the dura of the right frontal lobe. Immunohistochemistry revealed CD20- and CD43-positive B cells consistent with a low-grade B-cell lymphoma. The patient was diagnosed with stage I ocular adnexal MALT lymphoma and treated with radiation therapy, followed by systemic chemotherapy. However, an enhancing orbital and intracranial mass remained on follow-up imaging, leading to a repeat biopsy, which was consistent with a diagnosis of Rosai-Dorfman disease. This is the first reported pediatric case of ocular adnexal MALT lymphoma with subsequent development of Rosai-Dorfman disease.