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Established in 1998, the Asociacion de Hemato-Oncologia Pediatrica de Centro America (AHOPCA) is a consortium of pediatric oncology centers from Central American and Caribbean region countries, including Nicaragua, Guatemala, El [...], * Context.--Several countries of the Central America and Caribbean region have been sharing regional neuroblastoma (NB) treatment guidelines. However, there is no standardization in the diagnosis, subclassification, or tumor biology to aid in the risk stratification of these patients. Objective.--To examine the histology and assess the accuracy of the local pathology reports; to evaluate the usefulness of manual MYCN immunohistochemistry (IHC); and to use NB as a model to identify the needs to establish a central pathology review (CPR) program in this region. Design.--A retrospective CPR of specimens derived from patients with a diagnosis of NB and treated under the regional NB guidelines between 2012 and 2017 was conducted, allowing for a comparison between local diagnoses and the CPR diagnoses. Manual MYCN IHC was performed in the confirmed NB specimens and the results compared with known fluorescence in situ hybridization or automated IHC results, when available. Results.--The 156 specimens reviewed included 460 blocks and 183 original slides. Neuroblastoma was confirmed in 138 samples (88.5%), but low concordance rates for Shimada classification (n = 39; 25.0%), mitotic-karyorrhectic index (n = 4; 2.5%), and International Neuroblastoma Pathology Classification (n = 18; 11.5%) were noted. Manual MYCN IHC performed on 120 specimens showed conclusive results in 89.2% (28 positive, 23.4%; 79 negative, 65.8%) and questionable results in 10.8% (n = 13). Conclusions.--This retrospective CPR highlights the need for a CPR program to serve this region, to ensure correct diagnosis and subclassification of NB, and to provide manual MYCN IHC--with reflexing to fluorescence in situ hybridization, if questionable. This approach can further regional collaboration, enhance test utilization, and ultimately improve patients' outcomes. doi: 10.5858/arpa.2019-0570-0A

Neuroblastoma (NB) is the most common extracranial tumor of childhood. (1) It has a diverse clinical behavior ranging from metastatic disease with dismal patient outcome to tumor maturation or spontaneous [...], Context.--Neuroblastoma (NB) is the most common extracranial tumor of childhood. Although most cases have a distinctive histology, a subset of primitive cases require immunohistochemical studies to distinguish them from other small round blue cell tumors of childhood. Immunohistochemistry is also used to detect small amounts of tumor metastatic to the bone marrow and in posttreatment samples with obscuring fibrosis, calcification, or inflammation. The transcription factor PHOX2B is essential for the differentiation and survival of sympathetic neurons and chromaffin cells, and therefore is highly specific for the peripheral autonomic nervous system. Objective.--To determine the diagnostic utility of PHOX2B immunohistochemistry as a marker of primary, treated, and metastatic NB. Design.--Neuroblastoma tissue microarrays were stained with PHOX2B, CD57, and synaptophysin. Arrays containing rhabdomyosarcoma, Ewing sarcoma, and Wilms tumor were stained with PHOX2B, and negative bone marrow samples were stained with PHOX2B and CD57. Results.--PHOX2B and CD57 were similar to synaptophysin in their ability to detect NB. PHOX2B and CD57 similarly showed robust staining in posttreatment NB and NB metastatic to the bone marrow. In contrast to the cytoplasmic staining pattern seen with synaptophysin and CD57, clear and strong nuclear PHOX2B permitted identification of individual tumor cells. PHOX2B staining was absent in all cases of rhabdomyosarcoma, Ewing sarcoma, and Wilms tumor, and in the negative bone marrow. Conclusions.--PHOX2B and CD57 are useful markers of NB. PHOX2B is specific for NB in its differential diagnosis with other small round cell tumors, and its nuclear staining may be helpful for accurate bone marrow tumor quantification. (Arch Pathol Lab Med. 2015;139:543-546; doi: 10.5858/arpa.2014-0255-OA)