Chronic Lymphocytic Leukemia, T-Cell Large Granular Lymphocytic Leukemia in a Pediatric Patient without Underlying Condition

Background

Large granular lymphocytic (LGL) leukemia is a rare hematological malignancy in children. The two types of LGL leukemia that have been described are T-cell and Natural Killer cell leukemia. It is most commonly diagnosed in older adults, average age of 60-year-old. About 20 cases of LGL leukemia have been reported in children and young adults. All the patients in the reported cases had immune dysregulation conditions, such as chronic graft versus host disease, common variable immunodeficiency disorder, Crohn's disease and autoimmune hemolytic anemia. Here we report a case of T-cell LGL leukemia in a 11-year-old boy without underlying condition who presented with chronic neutropenia associated with gingival hypertrophy, recurrent skin abscesses, aphthous ulcers, clubbing of nails and low bone density.

Methods

Multi-institution collaboration and literature review.

Case Description

11-year-old male with two years history of episodic gum bleeding with gingival hypertrophy, skin abscesses, aphthous ulcers, chronic neutropenia and lymphocytosis presented to our clinic for further evaluation. Initial workup demonstrated moderate to severe neutropenia (absolute neutrophil count between 400/ul to 800/ul) with low segmented neutrophils of 2-4% and high lymphocytes of more than 80%, but normal white blood cell count, hemoglobin for age and platelet count. Peripheral blood smear showed several variant lymphocytes with cytoplasmic blebs and no immature cells present. Expansion of T-cell large granular lymphocytes were detected in peripheral blood by flow cytometry. Due to new symptom of lower back pain, a lumbar Magnetic Resonance Imaging was performed. Results showed low bone density with mild compression deformity of L1 and abnormal heterogeneous marrow signal with heterogeneous contrast enhancement. The abnormal bone marrow signal promoted the investigation of bone marrow aspiration and biopsy. Flow cytometry detected forty-five percent of lymphocytes with immuno-phenotype of CD3+, CD8+, CD57+, CD16+, CD7+ and CD5-. The morphology of minimal cytoplasm and mature chromatin along with immunophenotype were consistent with clonal T-cell large granular lymphocytic proliferation/leukemia. Further cytogenetic tests showed TCR gamma and beta genes rearrangement, STAT3 N647I mutation with normal male karyotype. A peripheral blood congenital neutropenia panel, which included a total of 18 genes, found a heterozygous mutation c 279 G>A in the Gata2 gene; a variant of uncertain significance. Next generation sequencing showed somatic mutations of TRGV10, TRGV8 TRGJ1, TNFAIP3 and STAT3. However, there was no germline mutations detected in sample from skin biopsy. Comprehensive evaluation by immunology, rheumatology and gastroenterology failed to detect any underlying conditions.

Conclusion

Due to rarity of LGL leukemia in pediatrics, standard of care guidelines are currently unavailable. Extrapolated from limited literature, two management options are considered: watch and wait approach versus early initiation of immunosuppressant chemotherapy. Improved diagnostics can aide management strategies in this patient population.