Improvement of diagnosis in children with Burkitt lymphoma in Kenya: feasibility study for the implementation of fluorescence in situ hybridisation testing for MYC and the MYC/IGH translocation.

Background: Indiana University (IU) initiated fluorescence in situ hybridisation (FISH) methodology for Burkitt Lymphoma (BL) to advance the accuracy and speed of diagnosis in the AMPATH Reference Laboratory at Moi Teaching and Referral Hospital (MTRH) in Eldoret, Kenya. Standard diagnostic testing for BL at MTRH includes morphology of the biopsy specimen or aspirate and limited immunohistochemistry panels. Methods: Tumour specimens from 19 children enrolled from 2016 to 2018 in a prospective study to improve the diagnosis and staging of children with suspected BL were evaluated. Touch preps from biopsy specimens or smears from fine needle aspiration were collected, stained with Giemsa and/or H&E and reviewed by pathologists to render a provisional diagnosis. Unstained slides were stored and later processed for FISH. Duplicate slides were split between two laboratories for analysis. Flow cytometry results were available for all specimens. Results from the newly established FISH laboratory in Eldoret, Kenya were cross-validated in Indianapolis, Indiana. Results: Concordance studies found 18 of 19 (95%) of specimens studied yielded analysable FISH results for one or both probe sets (MYC and MYC/IGH) in both locations. There was 94% (17/18) concordance of results between the two FISH laboratories. FISH results were 100% concordant for the 16 specimens with a histopathological diagnosis of BL and two of three non-BL cases (one case no result in IU FISH lab). FISH was similarly concordant with flow cytometry for specimens with positive flow results with the exception of a nasopharyngeal tumour with positive flow results for CD10 and CD20 but was negative by FISH. The modal turn-around time for FISH testing on retrospective study specimens performed in Kenya ranged between 24 and 72 hours. Conclusion: FISH testing was established, and a pilot study performed, to assess the feasibility of FISH as a diagnostic tool for the determination of BL in a Kenyan paediatric population. This study supports FISH in limited resource settings to improve the accuracy and speed of diagnosis of BL in Africa.

Signet-ring cell lymphoma: clinicopathologic, immunohistochemical, and fluorescence in situ hybridization studies of 7 cases.

CONTEXT: Signet-ring cell lymphoma (SRCL) is a rare morphologic variant of non-Hodgkin lymphoma. Although it was initially reported as a rare morphologic variant of follicular lymphoma (FL), SRCL has to date been described in most types of non-Hodgkin lymphoma, mostly as single-case reports. OBJECTIVE: To study SRCL systematically by immunohistochemical stains and fluorescent in situ hybridization analyses. DESIGN: Seven SRCL cases were stained for CD3, CD5, CD20, PAX-5, CD10, CD21, CD23, cyclin D1, BCL2, BCL6, Ki-67, and MUM-1, and were analyzed by fluorescent in situ hybridization for BCL2, BCL6, MYC, and MALT1 rearrangements. Clinical information and patient outcome were reviewed in all patients. RESULTS: The patients were 3 women and 3 men, ranging in age from 31 to 75 years (average 60.3 years). The lesions involved lymph nodes, tonsil, parotid gland, soft tissue, and breast. There were 4 FLs, 1 diffuse large B-cell lymphoma (DLBCL), 1 DLBCL with FL, and 1 DLBCL with marginal zone lymphoma. All cases had typical signet-ring cell morphology. They were positive for CD20 and BCL-2, and had low-to-intermediate Ki-67 proliferation index (10%-40%) except in the parotid DLBCL with FL (70%). BCL-6 was detected in all but 1 FL (6/7). Fluorescent in situ hybridization detected IGH/BCL2 translocation in 1 FL, increased BCL6 copy number in another FL, BCL6 rearrangement, and increased copy number of MYC and MALT1 in the DLBCL with marginal zone lymphoma. CONCLUSIONS: The FL with signet-ring cell morphology (1/5) tends to lack IGH/BCL2 translocation, and an extended immunohistochemical study is recommended for correct diagnosis and classification of SRCL.

Glioblastoma occurring at the site of a previous medulloblastoma following a 5-year remission period.

We describe a case of a 14-year-old boy who developed a cerebellar and brainstem glioblastoma 5 years after treatment for a medulloblastoma. The patient first presented in 2003 with 9 months of vomiting and a 9-kg weight loss. A head MRI showed a heterogeneously enhancing posterior fossa mass with hydrocephalus. Gross total resection was performed and the tumor was consistent with a classic medulloblastoma. Postoperative chemotherapy and craniospinal radiation was administered. The patient remained tumor-free until 2008, at which time he presented with right-sided weakness and numbness, left eye pain, vomiting and weight loss. Imaging showed abnormalities within the posterior pons, medulla, inferior cerebellar peduncles, cerebellar hemispheres and cervicomedullary junction with expansion of the medulla and cervical spinal cord. Due to the location of the lesion, biopsy was felt to be too risky and was avoided. Despite receiving chemotherapy, his symptoms continued to worsen and he died 4 months later. Post mortem examination limited to the brain and spinal cord confirmed the radiographic extent of the tumor. Microscopic examination showed a highly cellular infiltrative glial neoplasm with extensive palisading necrosis. A diagnosis of glioblastoma was rendered. The question of whether the first and second tumors were related is of potential clinical and academic interest. The first tumor was synaptophysin-positive and GFAP-negative, consistent with medulloblastoma. The second tumor was synaptophysin-negative and focally GFAP-positive, consistent with glioblastoma. The glioblastoma displayed EGF receptor amplification, and interestingly, it also displayed MYCN amplification; both tumors showed low level PTEN deletion. The medulloblastoma displayed a signal pattern consistent with an isochromosome 17q, while the glioblastoma showed some cells with an isochromosome 17q signal pattern amid a background of cells with abundant chromosomal instability. The relationship between these two tumors, particularly with regard to various molecular events, is discussed.