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Burkitt lymphoma (BL) is an aggressive form of B cell lymphoma that can affect children and adults. The study of BL led to the identification of the first recurrent chromosomal aberration in lymphoma, t(8;14)(q24;q32), and subsequent discovery of the central role of MYC and Epstein-Barr virus (EBV) in tumorigenesis. Most patients with BL are cured with chemotherapy but those with relapsed or refractory disease usually die of lymphoma. Historically, endemic BL, non-endemic sporadic BL and the immunodeficiency-associated BL have been recognized, but differentiation of these epidemiological variants is confounded by the frequency of EBV positivity. Subtyping into EBV

Mucoepidermoid carcinoma (MEC) is often seen in salivary glands and can harbor MAML2 translocations (MAML2+). The translocation status has diagnostic utility as an objective confirmation of the MEC diagnosis, for example, when distinction from the more aggressive adenosquamous carcinoma (ASC) is not straightforward. To assess the diagnostic relevance of MAML2, we examined our 5-year experience in prospective testing of 8106 solid tumors using RNA-seq panel testing in combinations with a two-round Delphi-based scenario survey. The prevalence of MAML2+ across all tumors was 0.28% (n = 23/8106) and the majority of MAML2+ cases were found in head and neck tumors (78.3%), where the overall prevalence was 5.9% (n = 18/307). The sensitivity of MAML2 for MEC was 60% and most cases (80%) were submitted for diagnostic confirmation; in 24% of cases, the MAML2 results changed the working diagnosis. An independent survey of 15 experts showed relative importance indexes of 0.8 and 0.65 for “confirmatory MAML2 testing” in suspected MEC and ASC, respectively. Real-world evidence confirmed that the added value of MAML2 is a composite of an imperfect confirmation test for MEC and a highly specific exclusion tool for the diagnosis of ASC. Real-world evidence can help move a rare molecular-genetic biomarker from an emerging tool to the clinic.

Context.—Nasopharyngeal carcinoma (NPC), common in southern China and North Africa, has a complex etiology involving interplay between viral, environmental, and hereditary factors and is almost constantly associated with the Epstein-Barr virus. Since the prognosis of locally advanced and metastatic diseases is poor, increased understanding of the pathogenesis of NPC would be important for discovering novel markers for patients' management.Objectives.—To compare the proteomic expression profile between an Epstein-Barr virus–associated NPC cell line (C666-1) and a normal NP cell line (NP69). The proteins with differential expression were analyzed in 40 undifferentiated NPC paraffin-embedded specimens.Design.—Differentially expressed proteins discovered between the two cell lines were identified by mass spectrometry. After confirmation by immunocytochemical staining, their expression in patient samples was measured using 40 pairs of undifferentiated NPCs together with their adjacent normal epithelia.Results.—Proteomic findings indicated that adenosine triphosphate synthase α chain was up-regulated, whereas annexin II, annexin V, β2-tubulin, and profilin 1 were down-regulated. After confirming the results in agar-processed cell lines, annexin II and β2-tubulin expression were found to be lower in tumor cells than in adjacent normal epithelial cells in 100% and 90% of the patients' specimens, respectively. Finally, annexin II down-regulation was positively associated with lymph node metastasis, suggesting that it may be a prognostic factor in NPC.Conclusions.—The results suggest that annexin II and β2-tubulin down-regulation is important in NPC formation and may represent potential targets for further investigations.

Context.—In immunohistochemistry, nonstandardized antigen retrieval protocols and fluids, poor-quality antibodies, and the presence of endogenous biotin frequently lead to incorrect results. Recently, advanced reagents including bifunctional SkipDewax pretreatment solution (BSPS), rabbit monoclonal (RM) antibodies, and biotin-free polymer detection systems (PDSs) have been developed, which, it is claimed, resolve these problems. Objectives.—To determine whether BSPS, RM antibodies, and biotin-free PDSs improve the accuracy of immunohistochemistry; to optimize a new protocol consisting of a combination of BSPS, RM antibodies, and PDSs; and to compare it with a conventional protocol. Design.—The efficacies of BSPS, RM antibodies, and PDSs were compared with those of their respective conventional reagents using multitissue spring-roll sections. The new protocol was compared with a conventional protocol using Ki-67 immunostaining of 49 colorectal carcinoma specimens. Results.—For antigen retrieval, BSPS resulted in similar or better tissue staining than an EDTA solution, but the efficacy of BSPS decreased when it was reused. Most RM antibodies resulted in a greater proportion of positive cells than the corresponding non-RM antibodies, which did not produce satisfactory results in the absence of antigen retrieval. The PDSs Bond, ChemMate, and SuperPicture resulted in a high percentage of positive cells, good staining intensities, and low backgrounds. Other PDSs, except that from Ventana, resulted in high backgrounds and false positivity. The new combined protocol resulted in better Ki-67 staining than the conventional assay. Conclusions.—Bifunctional SkipDewax pretreatment solution, RM antibodies, and PDSs improve staining quality and diagnostic accuracy of immunohistochemistry assays and provide a foundation for standardization.

Cotyledonoid leiomyoma or “grapelike” leiomyoma is a very rare tumor among the ever-expanding repertoire of growth variants described in benign uterine leiomyoma. We report a case of cotyledonoid leiomyoma in a 55-year-old woman who presented with menorrhagia and uterine prolapse. A large multinodular fungating tumor adhering to the right posterolateral wall of the uterus and extending to the broad ligament was discovered at vaginal hysterectomy. With a provisional diagnosis of sarcoma, total hysterectomy and bilateral salpingo-oophorectomy were performed. Postoperatively, the patient was well with no evidence of recurrence at 14 months. Pathologic examination revealed a 10-cm, red-brown tumor that comprised multiple bulbous processes protruding over the uterine surface, in continuity with a dissecting intramyometrial component. It was composed of fascicles and nodules of bland-looking smooth muscle cells with prominent perinodular hydropic degeneration. Coagulative necrosis, mitoses, and nuclear atypia were absent. Cotyledonoid leiomyoma apparently results from a combination of several uncommon growth patterns operating together, including subserosal growth, dissecting growth, and perinodular hydropic degeneration. Increased awareness of this grossly alarming variant of benign uterine leiomyoma can help avoid overtreatment.

Objective.—To study the expression of thyroid transcription factor 1 (TTF-1) and cytokeratin 20 (CK20) in pulmonary small cell carcinomas, extrapulmonary small cell carcinomas, and Merkel cell carcinomas, and thereby determine whether these markers are helpful in distinguishing these 3 groups of small cell neuroendocrine carcinomas.Materials and Methods.—Immunostaining for TTF-1 and CK20 was performed in 102 cases of small cell carcinoma (pulmonary, 52; extrapulmonary, 50) and 23 cases of Merkel cell carcinoma. The results for the 3 groups were compared.Results.—Thyroid transcription factor 1 was expressed in 82.7% of pulmonary small cell carcinomas, 42.0% of extrapulmonary small cell carcinomas (range, 33.3–53.3% for the various sites), and 0% of Merkel cell carcinomas. Cytokeratin 20 staining was consistently negative in pulmonary small cell carcinomas, and positive in 4.0% of extrapulmonary small cell carcinomas and 100% of Merkel cell carcinomas.Conclusions.—Immunostaining for TTF-1, especially when combined with immunostaining for CK20, can aid in the distinction between Merkel cell carcinoma and small cell carcinoma (both pulmonary and extrapulmonary). However, in individual cases, these markers cannot be used to distinguish between pulmonary and extrapulmonary small cell carcinomas due to the extensive overlap in immunophenotypes.

Three examples of an unusual morphologic variant of papillary thyroid carcinoma (PTC) are reported. The presence of a prominent stromal component resulted in low-power microscopic appearances resembling fibroadenoma, phyllodes tumor, or fibrocystic disease of the breast in two cases. The carcinomatous component grew in the form of anastomosing narrow tubules, clustered glands, solid sheets with or without squamous differentiation, and/or papillae, and exhibited the typical nuclear features of PTC. The abundant stroma had a nodular fasciitis-like quality and was composed of short fascicles of spindle cells separated by varying amounts of mucoid matrix, collagen, and extravasated red blood cells; this was interpreted as an exuberant mesenchymal reaction to the carcinoma. The importance of recognizing this variant of PTC is that, when one encounters a fibroproliferative lesion of the thyroid, a diligent search should be made for papillary carcinoma. This variant also must be distinguished from the vastly more aggressive papillary carcinomas with anaplastic transformation and the so-called carcinosarcomas.

Three cases of juvenile chronic myeloid leukemia (JCML) are reported. The patients were aged 3–4.5 years and presented with generalized lymphadenopathy, hepatosplenomegaly, anemia, thrombocytopenia, elevated white blood cell count with monocytosis, and high fetal hemoglobin level. Philadelphia chromo-some was absent in two cases studied. The bone marrow showed myeloid hyperplasia with increased monocytoid cells and blasts. Biopsy or postmortem material available in two cases revealed malignant infiltration of lymph nodes, liver, spleen, lungs, intestines, and skin. The neoplastic cells ranged from cells with irregular nuclei possessing nuclear grooves to large blastic cells with round to lobulated nuclei and prominent nucleoli. They showed weak staining for acid phosphatase and nonspecific esterase and exhibited the immunophenotype EBM11+KiM1+KiM6+KiM8+CD4+HLADR+ S-100 protein+. The neoplastic cells of JCML therefore share features of dendritic cells and mononuclear phagocytes. The authors’ findings show that JCML is a unique histiocytic malignancy in which S-100 protein is a useful marker.