Intraoperative frozen section histopathology for the diagnosis of periprosthetic joint infection in hip revision surgery: the influence of recent dislocation and/or periprosthetic fracture.

AIMS: To evaluate the accuracy of intraoperative frozen section histopathology for diagnosing periprosthetic joint infection (PJI) during hip revision surgery, both for patients with and without recent trauma to the hip. PATIENTS AND METHODS: The study included all revision total hip replacement procedures where intraoperative frozen section histopathology had been used for the evaluation of infection in a single institution between 2008 and 2015. Musculoskeletal Infection Society criteria were used to define infection. 210 hips were included for evaluation. Prior to revision surgery, 36 hips had a dislocation or a periprosthetic fracture (group A), and 174 did not (group B). RESULTS: The prevalence of infection was 14.3% (5.6% in group A and 16.1% in group B). Using Feldman criteria, the sensitivity of histopathology was 50.0%, specificity 47.1%, positive predictive value 5.3% and negative predictive value 94.1% in group A. The sensitivity of frozen section histopathology was 75.0%, specificity 96.5%, positive predictive value 85% and negative predictive value 95.3% in group B. CONCLUSIONS: Intraoperative frozen section histopathology is reliable for the diagnosis of PJI if no dislocation or periprosthetic fracture has occurred prior to hip revision surgery.

Anisometric Cell and Dysplastic Lipomas in a Retinoblastoma Patient.

Anisometric cell lipoma (ACL) and dysplastic lipoma (DL) are underrecognized subtypes of benign lipomatous tumors, with wide variation in cell size, microscopic fat necrosis, and no or mild nuclear changes (DL). ACL/DL appear more commonly in retinoblastoma patients, in whom an increased incidence of lipomas has been established. The occurrence of ACL/DL in retinoblastoma patients suggests that RB1 aberrations play a role in its pathogenesis, similar to spindle cell/pleomorphic lipoma. In this article, we present a patient with a history of retinoblastoma with multiple lipomas histologically consistent with ACL/DL. Analysis of the lipomas supports involvement of RB1 in the development of ACL/DL. Dysplastic changes were only seen in a single lipoma, which harbored an additional TP53 mutation. While providing further support for the occurrence of ACL/DL in retinoblastoma patients, we also suggest that DL is an ACL with TP53 mutation.

Pseudomyxoma peritonei originating from an intestinal duplication.

Alimentary tract duplications are rare congenital anomalies. They most often become symptomatic in childhood and rarely undergo malignant transformation. Pseudomyxoma peritonei (PMP) is an equally uncommon condition, most frequently originating from a primary appendiceal mucinous neoplasm. We report an extremely unusual case of PMP arising from an intestinal duplication. A 67-year-old woman presented with vague upper abdominal pain, and, unexpectedly, explorative laparoscopy revealed diffuse jelly-like peritoneal implants. The histopathological diagnosis of a low-grade PMP or "disseminated peritoneal adenomucinosis" was made. At that moment, no primary tumor was found. During later surgery, a cystic lesion located in the mesentery of the small bowel could be resected. Histologically, the cyst wall clearly showed the concentric layering of a normal bowel wall. The mucosa, however, displayed a diffuse low-grade villous adenoma. We concluded that this histological picture was most consistent with a small intestinal duplication, containing a low-grade villous adenoma. The adenoma caused a mucocele, which subsequently leaked or ruptured, giving rise to noninvasive mucinous peritoneal implants or low-grade PMP, also known as "disseminated peritoneal adenomucinosis" (DPAM).