Histopathological Diagnosis of Prosthetic Joint Infection: Does a Threshold of 23 Neutrophils Do Better than Classification of the Periprosthetic Membrane in a Prospective Multicenter Study?

No gold standard exists for histopathological diagnosis of a prosthetic joint infection (PJI). The historical criterion considers the presence of neutrophil infiltration upon examination of periprosthetic tissue. Morawietz et al. proposed a classification of periprosthetic membranes (Morawietz et al., Clin Pathol 59:591-597, 2006, https://doi.org/10.1136/jcp.2005.027458) and a more recently described classification with a new cutoff value of 23 neutrophils in 10 high-power fields (Morawietz et al., Histopathology 54:847-853, 2009. https://doi.org/10.1111/j.1365-2559.2009.03313.x). We performed a multicenter prospective study, which compared both methods for the diagnosis of PJI. All suspicions of PJI (n = 264) between December 2010 and March 2012 in seven centers were prospectively included. Five perioperative specimens were collected per patient for cultures, and one was collected for histology. Diagnosis of PJI was made according to the Infectious Diseases Society of America (IDSA) guidelines. Histopathological analysis classified the patients according to the threshold of 23 neutrophils and according to the classification of Morawietz. Performances of both methods were compared by using clinical and/or bacteriological criteria as the gold standard. Among 264 patients with suspected PJI, a diagnosis of infection was confirmed in 215 and unconfirmed in 49 patients. Histopathological analysis was available for 150 confirmed PJI and 40 unconfirmed PJI cases. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 78.7%, 90.0%, 96.7%, 52.9%, and 81.1%, respectively, for the Morawietz classification, and 82.0%, 90.0%, 96.9%, 57.1%, and 83.7%, respectively, for the 23-neutrophil threshold. The new algorithm using a threshold of 23 neutrophils can be proposed as a new gold standard for the histopathological diagnosis of PJI.

Plaque-Like Myofibroblastic Tumor: Report of 4 Cases.

Plaque-like myofibroblastic tumor of infancy was first characterized in 2007 by Clarke et al. In the first 2 cases described, large plaque-like tumors presented in the first 3 months of life exhibited microscopic features consistent with dermatofibroma but with immunohistochemical features of myofibroblastic lineage. In 2013, Marqueling et al reported 3 additional cases, 2 of which presented in early childhood, prompting the authors to recommend that the name of this condition be shortened to plaque-like myofibroblastic tumor. We present here 4 additional cases to better characterize clinical and histopathological features of this newly recognized entity. This benign lesion is of myofibroblastic lineage and demonstrates features consistent with multiple clustered dermatofibroma.

[Adipocytic tumors]. / Tumeurs adipeuses.

Adipocytic tumors are the most common mesenchymal neoplasms, liposarcoma accounting for approximately 20% of soft tissue sarcomas. The differential diagnosis between benign and malignant tumors is often problematic and represents a significant proportion of consultation cases. The goal of this article is to review liposarcoma subtypes, the main benign adipocytic neoplasms: lipoblastoma, hibernoma, spindle/pleomorphic cell lipoma, chondroid lipoma, as well as non adipocytic neoplasms with a lipomatous component such as lipomatous solitary fibrous tumor, emphasizing on practical differential diagnosis issues, and immunohistochemical and molecular tools allowing their resolution.

Nationwide incidence of sarcomas and connective tissue tumors of intermediate malignancy over four years using an expert pathology review network.

BACKGROUND: Since 2010, nationwide networks of reference centers for sarcomas (RREPS/NETSARC/RESOS) collected and prospectively reviewed all cases of sarcomas and connective tumors of intermediate malignancy (TIM) in France. METHODS: The nationwide incidence of sarcoma or TIM (2013-2016) was measured using the 2013 WHO classification and confirmed by a second independent review by expert pathologists. Simple clinical characteristics, yearly variations and correlation of incidence with published clinical trials are presented and analyzed. RESULTS: Over 150 different histological subtypes are reported from the 25172 patients with sarcomas (n = 18712, 74,3%) or TIM (n = 6460, 25.7%), with n = 5838, n = 6153, n = 6654, and n = 6527 yearly cases from 2013 to 2016. Over these 4 years, the yearly incidence of sarcomas and TIM was therefore 70.7 and 24.4 respectively, with a combined incidence of 95.1/106/year, higher than previously reported. GIST, liposarcoma, leiomyosarcomas, undifferentiated sarcomas represented 13%, 13%, 11% and 11% of tumors. Only GIST, as a single entity had a yearly incidence above 10/106/year. There were respectively 30, 64 and 66 different histological subtypes of sarcomas or TIM with an incidence ranging from 10 to 1/106, 1-0.1/106, or < 0.1/106/year respectively. The 2 latter incidence groups represented 21% of the patients with 130 histotypes. Published phase III and phase II clinical trials (p<10-6) are significantly higher with sarcomas subtypes with an incidence above 1/106 per. CONCLUSIONS: This nationwide registry of sarcoma patients, with exhaustive histology review by sarcoma experts, shows that the incidence of sarcoma and TIM is higher than reported, and that tumors with a very low incidence (1<106/year) are less likely to be included in clinical trials.

Portal vein leiomyosarcoma: A rare case of hepatic hilar tumor with review of the literature.

Portal vein leiomyosarcoma (LMS) is a very rare entity with poor prognosis. Only few cases have been reported in the literature. We report the case of a 53-year-old man with portal vein LMS presenting as a hilar tumor and causing cholestasis. The tumor measured 10 cm and was responsible for right portal vein thrombosis and compression of the biliary convergence. A right hepatectomy with hilar en bloc resection was performed with portal vein and biliary reconstruction. Pathology confirmed the complete resection of a well-differentiated leiomyosarcoma of the portal vein. The postoperative outcome was uneventful and the patient received no adjuvant treatment. Six months after the procedure, the patient is doing well with a normal quality of life and without any sign of recurrence. Aggressive and radical surgery should be proposed in first intention for the treatment of portal vein LMS.

Ultrasound-guided synovial biopsy improves diagnosis of septic arthritis in acute arthritis without enough analyzable synovial fluid: a retrospective analysis of 176 arthritis from a French rheumatology department.

To assess the diagnostic value of ultrasound-guided (US-guided) synovial biopsy in routine clinical practice in cases of acute and chronic arthritis. A retrospective, single-center study of US-guided synovial biopsies between 2003 and 2013. The clinical, laboratory, radiographic, synovial fluid, and histological and bacteriological results of synovial biopsies were analyzed. Arthritis was classified according to disease duration < 6 weeks (AA) or ≥ 6 weeks (CA). Synovial biopsy success rate was defined by the rate of capsular and/or synovial tissue analyzed. The diagnostic efficiency was defined by synovial biopsy success rate multiplied by the clinical utility (validation of a diagnostic hypothesis leading to a specific therapy). One hundred seventy-six US-guided synovial biopsies (51 AA and 125 CA) were analyzed. Synovial biopsy success rate was 82.4%. The diagnostic efficiency was 19.9%. Among the acute arthritis cases, 11 were septic. Only three patients had a positive biopsy culture while the synovial fluid puncture was of insufficient quantity to allow bacteriological analysis. The perivascular infiltration of neutrophils (PMN) had a sensitivity of 81.8%, a specificity of 84.2%, and a positive likelihood ratio of 5.2 for the septic arthritis diagnosis. Among the chronic arthritis cases, no case of pyogenic septic arthritis was found. No histological lesions, examined separately, were specific to a type of chronic inflammatory joint disease. US-guided synovial biopsies remain relevant for the diagnosis of septic arthritis, in cases of acute arthritis when joint aspiration is not possible.

Maintaining a regular physical activity aggravates intramuscular tumor growth in an orthotopic liposarcoma model.

Today, care teams within cancer centers encourage patients to be physically active, after diagnosis, based on data obtained mainly from breast, colon and prostate cancer. Intriguingly, the impact of physical activity (PA) on intramuscular tumors (e.g. sarcomas) has not been specifically addressed and, thus, could be mistakenly confounded with other cancers. In this preclinical study we assessed the impact of PA on intramuscular liposarcoma (LS) evolution. Four-week-old nude male mice were active by voluntary running on wheels, for six weeks. Then, mice were divided into four groups with open or restricted access to wheels, which have received an orthotopic intramuscular injection of either vehicle or human LS, SW872, cells. Active mice presented ~1.5 fold increase in tumor mass, which was mainly due to higher cellular mitosis and proliferation. This bulging intramuscular tumor mass altered muscle function, as evidence by overall muscle strength and maximum running capacity. From a molecular point of view, active mice exhibited poor levels of Phospho-p38Thr180/Tyr182 and p21 content in tumors and also displayed low amounts of circulating insulin comparing to inactive counterparts. Insulin induced Phospho-p38Thr180/Tyr182 and p21 expression in SW872 cells, in vitro. The expression of p21 was regulated in a p38-dependent fashion, since inhibition of p38 activity abolished the up-regulation of p21. Our data suggest that insulin-dependent activation of p38 MAPK-p21 pathway is a possible mechanism responsible for delaying tumor growth in inactive mice. Clinically, patients with lower-extremities LS could be advised to reduce or minimize their levels of PA during the preoperative period.

Differential diagnosis of atypical lipomatous tumor/well-differentiated liposarcoma and dedifferentiated liposarcoma: utility of p16 in combination with MDM2 and CDK4 immunohistochemistry.

The differential diagnosis between atypical lipomatous tumor/well-differentiated liposarcoma (ALT/WDLPS) and dedifferentiated liposarcoma (DDLPS) from their morphologic counterparts is challenging. Currently, the diagnosis is guided by MDM2 and CDK4 immunohistochemistry (IHC) and is confirmed by the amplification of the corresponding genes. Recently, p16 IHC has been proposed as a useful diagnostic biomarker. The objective was to assess the utility of p16 IHC in the differential diagnosis of ALT/WDLPS and DDLPS. Our series included 101 tumors that were previously analyzed using fluorescence in situ hybridization for MDM2 and CDK4 amplification. We compared sensitivity and specificity of p16 IHC to MDM2 and CDK4 IHC in the differential diagnosis of ALT-WDLPS (n=19) versus benign adipocytic tumors (n=44) and DDLPS (n=18) versus mimicking sarcomas (n=20). In the differential diagnosis of ALT-WDLPS, p16 had a sensitivity of 89.5% but a specificity of 68.2%, which was impaired by false-positive lipomas with secondary changes, especially in biopsies. Likewise, in the differential diagnosis of DDLPS, p16 had a sensitivity of 94.4% and a specificity of 70%, which hampered its use as a single marker. However, adding p16 to MDM2 and/or CDK4 increased diagnostic specificity. Indeed, MDM2+/p16+ tumors were all ALT-WDLPS, and MDM2-/p16- tumors were all benign adipocytic tumors. Moreover, all MDM2+/CDK4+/p16+ tumors were DDLPS, and the MDM2-/CDK4-/p16- tumor was an undifferentiated sarcoma. Although the use of p16 as a single immunohistochemical marker is limited by its specificity, its combination with MDM2 and CDK4 IHC may help discriminate ALT-WDLPS/DDLPS.

A new subtype of high-grade mandibular osteosarcoma with RASAL1/MDM2 amplification.

In contrast to long bone osteosarcoma, mandibular osteosarcoma is highly heterogeneous and morphologically overlaps with benign tumors, obscuring diagnosis and treatment selection. Molecular characterization is difficult due to the paucity of available specimens of this rare disease. We aimed to characterize the spectrum of mandibular osteosarcoma using immunohistochemistry and molecular techniques (quantitative polymerase chain reaction and sequencing) and compare them with benign fibro-osseous lesions. Forty-nine paraffin-embedded mandible osteosarcoma tissue samples were collected retrospectively and compared with 10 fibrous dysplasia and 15 ossifying fibroma cases. These were analyzed for molecular markers thought to differ between the different diseases and subtypes: MDM2 (murine double-minute type 2) overexpression, GNAS (guanine nucleotide-binding protein/α subunit) mutations, and amplification of MDM2 and/or RASAL1 (RAS protein activator like 1). Five fibroblastic high-grade osteosarcoma subtypes showed MDM2 amplification, including 2 with a microscopic appearance of high-grade osteosarcoma with part low-grade osteosarcoma (differentiated/dedifferentiated osteosarcoma) and MDM2 overexpression. The other 3 contained a coamplification of MDM2 and RASAL1, a signature also described for juvenile ossifying fibroma, with no overexpression of MDM2. These were of the giant cell-rich high-grade osteosarcoma, with areas mimicking juvenile ossifying fibroma (ossifying fibroma-like osteosarcoma). Our results show that some diagnosed high-grade osteosarcomas are differentiated/dedifferentiated osteosarcomas and harbor an overexpression and amplification of MDM2. In addition, juvenile ossifying fibromas can potentially evolve into giant cell-rich high-grade osteosarcomas and are characterized by a RASAL1 amplification (osteosarcoma with juvenile ossifying fibroma-like genotype). Thus, the presence of a RASAL1 amplification in ossifying fibroma may indicate a requirement for closer follow-up and more aggressive management.

Multicentric pleomorphic xanthoastrocytoma in a patient with neurofibromatosis type 1. Case report and review of the literature.

The authors report an unusual case of multicentric pleomorphic xanthoastrocytoma (PXA) in a 36-year-old woman with neurofibromatosis Type 1 (NF1). Both lesions were diagnosed as PXA but demonstrated different neuroimaging features and very different outcomes. Although the occipital lesion was cured surgically, the cerebellar tumor recurred three times and underwent malignant transformation into an anaplastic oligodendroglioma. The authors discuss the causes of PXA and suggest that it could originate from common bipotential precursor cells with two phenotypes.

[Multicentric reticulohistiocytosis: report of a case with systemic disease]. / Réticulohistiocytose multicentrique: a propos d'un cas avec atteinte systémique.

Multicentric reticulohistiocytosis (RHM) is a rare non Langherhans cell histiocytosis with skin and joint involvment. Nearly all organs can be involved. Association with cancer occurs in about 25% of cases. Association with auto-immune diseases has also been recorded. Microscopic examination shows a histiocytic nodular infiltrate made of giant cells with ground-glass appearance and PAS positive cytoplasm. Immunostaining shows cell positivity for CD68 and negativity for CD1a and S100 protein. No Birbeck granules are found at ultrastructural examination.

Aspergillus arthritis and organ transplantation.

We report a case of a kidney and pancreas transplanted patient, hospitalized for septic hip arthritis. The whole diagnostic work-up including synovial and bone biopsies remained negative. After inefficient empirical anti-bacterial antibiotic treatment, femoral head resection was performed and tissue analysis revealed Aspergillus fumigatus hyphae. Treatment with voriconazole along with hip replacement led to complete recovery. However, drug interaction between immunosuppressive and anti-fungal drugs was complicated by cellular acute graft rejection. Aspergillus fumigatus arthritis is an uncommon and serious infection that should be evoked especially in the case of resistance to anti-microbial antibiotics and/or an atypical clinical picture.

Nucleic acid quality preservation by an alcohol-based fixative: comparison with frozen tumors in a routine pathology setting.

Pathologic diagnosis requires tissue fixation for histologic and immunohistologic analysis, and formalin is routinely used for this. The disadvantage of this fixative is its inability to preserve nucleic acids. Pathologic tumor diagnosis requires extensive molecular analyses, for which formalin fixation may be not adequate. Recently, an alcohol-based fixative (molecular fixative, MF) was described that allows nucleic acid preservation as well as histologic and immunohistologic studies. Moreover, the MF fixation processing system (Xpress) is fast and is well adapted to a routine process. We evaluated RNA and DNA quality within 1 month and after 1 year for 10 breast carcinomas and 20 sarcomas fixed in MF in comparison with the corresponding frozen tumors. The quality of DNA extracted from the MF-fixed tissue was similar to that extracted from the frozen tumors. The quality of RNA extracted from the MF-fixed tissue was lower than that of frozen tumors; nevertheless, a majority of RNA integrity number (RIN) values were greater than 7. Gene expression quantification by real-time polymerase chain reaction gave comparable results between tumors fixed with MF and frozen tumors. Tissue fixation at 4°C with the MF improved the RNA quality measured by the RIN value. However, after storage for 1 year at room temperature, although DNA quality was preserved, RNA extracted from tissues fixed with the MF was degraded. Tissue fixation with the MF is an important improvement for molecular pathologic diagnosis, enabling a combination of routine pathologic diagnoses and current molecular diagnoses if they are carried out near the processing time.

The biology of melanoma prognostic factors.

Cutaneous melanoma still represents a paradox among all solid tumors. It is the cancer for which the best prognostic markers ever identified in solid tumors are available, yet there is very little understanding of their biological significance. This review focuses on recent biological data that shed light on the clinical-biological correlations underlining the 2010 American Joint Committee on Cancer (AJCC) melanoma staging system. A major challenge is to replace outcome clustering based on artificial biomarker breakpoints by a continuous multidimensional prognostic model. Major improvement will come from shared computerized tools that allow the generation of continuous likelihood scores for diagnosis, prognosis, and response prediction. This will lead to the development of platforms which can be used by scientists from different fields to integrate and share high-quality data in the pre-competitive setting and generate new probabilistic causal models.