Angiomatoid fibrous histiocytoma (AFH) is a rare soft tissue tumor of intermediate biologic potential. Because of its rarity and nonspecific radiological and diverse pathological findings, AFH is often clinically misdiagnosed. However, few clinical reports have described this tumor. As reported herein, we analyzed the clinical and radiological features and clinical outcomes of AFH. We retrospectively reviewed the medical records of seven cases histopathologically diagnosed as AFH. We examined clinical features, MRI findings, histopathological diagnoses, treatments, and outcomes. These seven cases comprised five male and two female patients with ages ranging from 8 to 50 years old. The primary locations included upper extremities in 2, lower extremities in 4, and the inguinal region in one patient. Of the tumors, 4 occurred in subcutaneous tissues and 3 occurred in deep tissues. No cases were diagnosed as AFH from MRI and needle biopsy results. All cases were diagnosed histopathologically after excision. After treatment, 2 patients (29%) had tumor recurrence and metastasis, one of whom died from disease progression. These 2 aggressive cases involved both EWSR1 and CREB1 gene rearrangements as determined by FISH. The other patients were alive and well without recurrence or metastasis. AFH is a rare tumor that is difficult to diagnose. Therefore, it tends to be misdiagnosed and to be treated inadequately by referring physicians. Surgeons must therefore be mindful of the presence of AFH, learn about appropriate treatment necessary for this tumor, and conduct careful follow-up because AFH can engender poor outcomes.

Myxoid liposarcomas (MLSs) are genetically defined by the presence of DDIT3 gene fusions and most commonly arise in the extremities of young adults. Whether MLSs develop primarily in the retroperitoneum is controversial, and a recent retrospective study found no molecularly confirmed examples. Because MLSs tend to metastasize to deep soft tissues, purported examples of primary retroperitoneal lesions might represent distant metastasis, most commonly from extremities. In addition, well-differentiated or dedifferentiated liposarcomas, which are characterized by MDM2 amplifications, may exhibit prominent myxoid changes and mimic MLSs. Here, we document 5 cases of MLSs that originated in the retroperitoneum that were identified through critical clinicopathologic reevaluation. These cases accounted for 2.3% of 214 primary retroperitoneal liposarcomas and 3.2% of 156 MLSs in our database. They occurred in 3 men and 2 women with a median age of 32 years. All tumors were localized to the retroperitoneum at presentation, and no patient developed extra-abdominal recurrences during the clinical course (median, 50 mo). All 5 cases exhibited at least focal classic histologic findings. All harbored DDIT3 gene rearrangements, and none harbored MDM2 amplifications according to fluorescence in situ hybridization. This study demonstrates that primary MLSs can occur in the retroperitoneum, albeit rarely, and can be accurately diagnosed through combined clinicopathologic and molecular analysis.

Osteosarcoma (OS) is an aggressive mesenchymal tumor for which no molecularly targeted therapies are available. We have previously identified TRAF2- and NCK-interacting protein kinase (TNIK) as an essential factor for the transactivation of Wnt signal target genes and shown that its inhibition leads to eradication of colorectal cancer stem cells. The involvement of Wnt signaling in the pathogenesis of OS has been implicated. The aim of the present study was to examine the potential of TNIK as a therapeutic target in OS. RNA interference or pharmacological inhibition of TNIK suppressed the proliferation of OS cells. Transcriptome analysis suggested that a small-molecule inhibitor of TNIK upregulated the expression of genes involved in OS cell metabolism and downregulated transcription factors essential for maintaining the stem cell phenotype. Metabolome analysis revealed that this TNIK inhibitor redirected the metabolic network from carbon flux toward lipid accumulation in OS cells. Using in vitro and in vivo OS models, we confirmed that TNIK inhibition abrogated the OS stem cell phenotype, simultaneously driving conversion of OS cells to adipocyte-like cells through induction of PPARγ. In relation to potential therapeutic targeting in clinical practice, TNIK was confirmed to be in an active state in OS cell lines and clinical specimens. From these findings, we conclude that TNIK is applicable as a potential target for treatment of OS, affecting cell fate determination.

This study was undertaken to clarify the risk factors, including the mutation status of CTNNB1 , for the local recurrence after surgery of the rare disease desmoid‐type fibromatosis. It was designed as a multiinstitutional joint research project with 7 major centers in Japan participating. The committee members of 7 major medical centers specializing in bone and soft tissue tumors formed this study group to develop clinical care guidelines. Of 196 cases with specimens and medical records collected from the 7 institutions, 88 surgically treated ones were analyzed regarding clinicopathologic prognostic factors including CTNNB1 mutation status. Excluding R2 cases (n = 3), 5‐year local recurrence‐free survival (LRFS) was 52.9%. No case had received pre‐ or postoperative radiotherapy. Univariate analysis revealed that extremity location (P < .001) and larger size (8 cm or more, P = .036) were significant adverse risk factors for LRFS. Multivariate analysis indicated that extremity location (P < .001) was a significantly adverse factor in addition to recurrent tumor (P = .041), S45F mutation (P = .028), and R1 surgical margin (P = .039). Preoperative drug treatment, including nonsteroidal antiinflammatory drugs, did not reduce the incidence of local recurrence (P = .199). This is the first study to analyze the factors correlating with outcomes of surgical treatment, including CTNNB1 mutation status, in a relatively large number of cases from an Asian country. Tumor location was found to be the most influential prognostic factor for local recurrence, similar to the results from Europe and North America. The development of more sensitive method(s) for determination of CTNNB1 mutation is a priority for future study.