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To present the morphological changes of classic primary versus rapidly progressive and secondary hip osteoarthritis (HO) and to examine the expression of two pluripotent mesenchymal stem cell-like markers in the synovial membrane. A prospective observational study was conducted in 57 consecutive cases of radiologically confirmed HO in which total hip arthroplasty was performed. Based on the radiological and clinicopathological features, the cases were divided into three categories: classic primary HO (group A; n=16), rapidly destructive HO (group B; n=24), and HO secondary to avascular osteonecrosis of the femoral head (group C; n=17). Immunostains were performed using the markers CD44 and CD105. The cases from group A were mainly characterized by a marked perivascular inflammatory infiltrate and simple synovial hyperplasia. In group B, the papillary type of synovial hyperplasia was found and presence of chondromatosis, ossification, and ectopic follicles with germinal centers in the subsynovial layer was characteristic, whereas marked calcification and/or ossification were seen in group C. Focal expression of the CD105 and CD44 was noted in the hyperplastic synovial cells and subsynovial layer in cases from group A, whereas synovial cells from group B were diffusely positive for both CD44 and CD105. In secondary HO, CD44 marked the inflammatory cells. Mobilization of the CD44/CD105 positive synovial cells seems to play a role in the genesis of HO. The number of the pluripotent mesenchymal stem cell-like cells derived from the hyperplastic synovial cells might be related to the severity of possible immune-mediated rapidly destructive HO.

Atypical hepatocellular neoplasm (AHN) is an adenoma-like hepatic tumor that even occurs in noncirrhotic liver of males (any age) or females ≥50 years old, or associates focal atypical features.In this article, 2 unusual cases diagnosed in elderly cirrhotic patients, unrelated to steroids, are presented.The first case was incidentally diagnosed in an 83-year-old female. During laparoscopic surgery for cholecystectomy, hemoperitoneum was installed and laparotomy was necessary to remove a 70-mm nodular encapsulated hepatic tumor that was microscopically composed by hepatocyte-like cells with clear cytoplasm, arranged in 1- to 2-cell-thick plates and intermingled with areas of peliosis, negative for alpha fetoprotein (αFP), p53, and keratin 7, with low Ki67 index and intact reticulin framework. The second case was incidentally diagnosed at ultrasound examination in a 66-year-old male. The surgical specimen was a 50-mm solid multinodular tumor that microscopically consisted of 3-cell-thick plates of hepatocyte-like cells with acinar, pseudoglandular, and trabecular architecture, intermingled with peliotic areas, without nuclear atypia and disintegrated reticulin framework. Both of the cases occurred in cirrhotic liver. The tumor cells were marked by AE1/AE3 keratin, displayed a Ki67 index < 5% and were negative for αFP, p53, and keratin 7. No recurrences or any other disorder occurred 6 months after surgery.In cirrhotic liver, adenomas with peliosis that do not satisfy all the diagnosis criteria synthesized in the article should be considered AHNs and differential diagnosis includes hepatocellular carcinoma but also focal nodular hyperplasia, regenerative nodules, and dysplastic nodules. This histological entity is not yet included in the WHO Classification list.

Rationale:Burkitt lymphoma (BL) is an endemic tumor in Africa but rare sporadic cases are diagnosed in Europe.Patient concerns:A 60-year-old woman was hospitalized with fulminant hematemesis and a history of recurring melena.Diagnoses:The upper gastrointestinal endoscopy revealed a tumor of the antrum.Interventions:Emergency gastrectomy was performed.Outcomes:Gross findings revealed an ulcerated tumor with elevated margins and several perigastric and extragastric lymph nodes. Histological examination showed proliferation of atypical lymphocytes with a Ki67 index of 100%; they were marked by CD20, CD79a, bcl-6, and CD10 and were negative for CD3, CD5, CD23, TdT, bcl-2, and Cyclin D1. The tumor cells crossed the serosa and presented invasion of the lymph nodes. The patient died 10 days after surgery due to bronchopneumonia and acute renal failure.Lessons:In our department, only one gastric BL was diagnosed in a 61 consecutive lymphomas of the gastrointestinal tract (1.64%). Less than 200 reports about gastric-BL have been published to date. This case highlights the difficulty of diagnosis of rare variants of aggressive gastric lymphomas in medium-income countries without screening programmes.