[1353] An Unusual Presentation of Precursor B Acute Lymphoblastic Leukemia (B-ALL) with No Circulating Blasts, Scant Marrow Involvement, and Paratrabecular Localization of Blasts

Mir B Alikhan, Jennifer McNeer, Ira Miller, Elizabeth Hyjek, John Anastasi. University of Chicago Hospitals, Chicago, IL; Rush University, Chicago, IL

Background: B-ALL usually presents with circulating blasts and a hypercellular marrow packed with blasts. Less commonly it is hypoplastic with low cellularity of mostly blasts, necrotic with ghost cells, or associated with eosinophilia and t(5;14). We identified an unusual presentation in 3 patients who had no circulating blasts, scant marrow involvement and paratrabecular disease which initially precluded a definitive diagnosis. We report these to characterize and bring attention to this presentation.
Design: We reviewed clinical and lab data, as well as morphologic, immunophenotypic and genetic findings.
Results: The patients were 15, 8 and 3 years of age and presented with viral hepatitis; a history of a viral syndrome with fever/malaise; or several weeks of fever/sore throat/lymphadenopathy (reactive by biopsy), then gastroenteritis. All had cytopenias but no circulating blasts. The marrows were hypercellular with megakaryocytic/erythroid hyperplasia with reactive lymphoid nodules (in 2) and scant blastic infiltrates (<5-20%) that were paratrabecular/para-sinusoidal and associated with V-CAM1+ endothelial cells of a bone marrow vascular niche. The cells were more mature-appearing than typical blasts and had irregular/clefted nuclei. The cells were TdT+,CD19+,CD10+ and variably CD20+ resembling hematogones. Hyperdiploidy was seen in 2 cells (13%) in one and in 1 cell (3%) in another; the 3rd had a normal karyotype at presentation. A diagnosis of B-ALL was suspected but not made due to less than definitive features. After 2nd or 3rd marrows over 3-5 weeks, a diagnosis was made in each with more extensive disease and more obvious genetic clones (hyperdiploid in 2; dic(9;20)(p11;q11.1),+21 in the 3rd).
Conclusions: Paratrabecular marrow localization is seen in follicular, mantle cell and lymphoplasmacytic lymphoma and is felt to be due to homing to a marrow niche. Such a pattern has not been reported in ALL. The paratrabecular localization, scant marrow involvement and lack of circulating blasts may complicate/delay an initial diagnosis. The development of more extensive disease suggests that the presentation may just be 'early'. However, the scant leukemic infiltrate in light of cytopenia, marrow hyperplasia, reactive lymphoid nodules and history of viral illness raises the possibility that an infection-associated immune reaction can alter the usual presentation of B-ALL.
Category: Hematopathology

Monday, March 19, 2012 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 234, Monday Morning


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