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Angiomatoid fibrous histiocytoma (AFH) is a rare tumor of intermediate malignancy. Treatment options for unresectable and/or metastatic tumors are very limited. Immunotherapy with PD-1/PD-L1 inhibitors may be worth exploring. The aim of this study was to evaluate the expression of PD-L1 in AFHs. PD-L1 expression was assessed on 36 AFHs from 36 pediatric patients by immunohistochemical staining of PD-L1 (clone 22C3). Positivity was defined as membranous expression in ≥ 1% of either tumor or immune cells. The correlations between PD-L1 expression and clinicopathologic features were assessed. Two patients had lymph node metastasis. All patients underwent surgical resection; three of them also had systemic chemotherapy. Three patients had recurrence after initial resection; all patients were alive with a median follow-up of 2.5 years. Overall, twenty-two (61%) tumors were positively stained for PD-L1 and positivity was seen on both tumor and immune cells in eighteen of the 22 tumors. A positive correlation was found between tumor cell PD-L1 expression and CD8+ T-cell infiltration. There were no statistically significant differences between the status of PD-L1 expression and the clinicopathological features assessed. PD-L1 expression was identified in 61% of AFHs with a predominantly adaptive pattern. Our findings provide a rationale for future studies evaluating the potential of checkpoint immunotherapy for patients with unresectable and/or metastatic tumor.

Fibrous histiocytoma (FH) or dermatofibroma is a common cutaneous lesion mostly seen in adults and rare in the first two years of life. Two hundred sixty-seven patients younger than 18 years with a diagnosis of FH or dermatomyofibroma, a lesion with morphologic overlap with FH, were identified from the files of a single institution, with only 13 (4.8%) occurring in patients younger than 5 years. Ten patients had either underlying neurologic, autoimmune, or metabolic disorders or a family history of autoimmune conditions. Histologic review of hematoxylin and eosin staining and immunostaining on 75 FHs and dermatomyofibroma in 70 patients showed the following results: 33 classic FHs, 8 classic FHs characterized by a peculiar retiform morphology with thin fascicles of elongated cells forming a network reminiscent of the eruptive variant of FH, 19 deep/cellular variants, 5 aneurysmal variants, 3 lipidized variants (including two lesions in a patient affected by mucopolysaccharidosis IV), 3 dermatomyofibromas, and 4 isolated cases of hemosiderotic, granular cell atypical, and epithelioid FH. Immunostaining for factor XIIIa highlighted a dense network of dendritic cells in FH, which was significantly reduced in the FH with retiform morphology. Smooth muscle actin staining was positive in a high percentage of FHs (85.3%). The current series demonstrates that FH in children may show unique clinical and morphologic features. The retiform pattern with decreased dendritic cells found in congenital lesions and in two older patients with lesions in two locations might have a different pathogenesis, probably related to an altered immune response in very young patients., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Malignant fibrous histiocytoma (MFH), a high-grade, undifferentiated sarcoma, is highly aggressive, resistant to radiochemotherapy and associated with poor prognosis. There are no specific immunohistochemical markers for its diagnosis. The MFH cell line SFT7913 served as and immunogen for the generation of the FU3 monoclonal antibody in our laboratory. FU3 reacted strongly with MFH cells and with perivascular mesenchymal cells. In this study, we demonstrated that the antigen recognized by FU3 was identical to aminopeptidase N (APN/CD13) using FU3 immunoaffinity chromatography and N-terminal amino acid sequencing. Frequent (80%) and high-grade (>50% of cells) expression of APN/CD13 was observed in MFH, although low-grade expression was seen in some other sarcomas. Moreover, small interfering RNA (siRNA) that specifically targets APN/CD13 significantly suppressed MFH cell invasion in vitro. The newly developed monoclonal antibody FU3 specifically recognizes CD13 on MFH cells. Decreased expression of CD13, mediated by siRNA-mediated knockdown, attenuated the invasive capacity of MFH cells. Thus, results indicate that APN/CD13 could be an important diagnostic biomarker and therapeutic target for MFH.

Takayasu arteritis (TA) is a type of systemic large-vessel vasculitis that usually affects the aorta and its major branches. It remains unrecognized owing to delayed diagnosis (Boltin et al. in Rheumatol Int 27(10):985-987, 2007) and non-characteristic clinical features. It has been described in association with many autoimmune diseases, such as inflammatory digestive tract diseases. However, report of TA associated with tumors, especially malignant tumors, are rare. We here presented a case diagnosed by both Takayasu arteritis and malignant fibrous histiocytoma, from which we learned not only clinical lessons, but also consensus of relationships between these two diseases.

Angiomatoid fibrous histiocytoma (AFH) is an uncommon and mostly indolent soft tissue neoplasm, which usually occurs in the subcutaneous tissue of the extremities in children and young adults. Although the histologic features of AFH are well established, reports of its cytomorphology are very limited. This report characterizes the cytomorphologic features of five cases of AFH, with correlation to clinical, histology, and cytogenetic findings. Smears of fine needle aspiration (FNA; four cases) and intraoperative scrape (one case) were reviewed from five patients with a histologically confirmed diagnosis of AFH. A review of six previously reported AFH cases with cytomorphology was also performed. The tumor presented as a cystic, deep dermal mass in three pediatric cases and as a solid, deeply seated mass in two adults. The cytomorphologic features are mostly nondistinctive and include cellular smears with ovoid to spindled histiocytoid cells that may be isolated or in clusters. Some of these cells are atypical and others contain hemosiderin. Large cellular clusters with a capillary structure and a whorled arrangement of tumor cells can be appreciated in some cases. There is always a bloody background, but a lymphoplasmacytic infiltrate is uncommon. The presences of EWSR1 rearrangement in one case and three copies of FUS gene in another case were detected by fluorescence in situ hybridization. Diagnosing AFH by FNA cytology alone can be challenging because of its rarity and usually nonspecific cytologic findings. Clinical correlation and ancillary studies are essential to reach a specific diagnosis of AFH in small needle biopsies., (Copyright © 2011 Wiley-Liss, Inc.)

Background: Atypical fibroxanthoma (AFX) and undifferentiated pleomorphic sarcoma (UPS) are uncommon, spindle cell cutaneous malignancies. Solid organ transplant recipients (SOTRs) are immunosuppressed and therefore have a higher incidence of cutaneous malignancies., Objective: We describe the clinical spectrum of AFX and a more-aggressive, deeper variant, UPS, in SOTRs., Materials and Methods: A retrospective chart review of AFX and UPS in SOTRs was implemented. Cases from Vanderbilt University, Emory University, Mayo Clinic-Jacksonville, and University of Rochester were included. A literature search included previously published cases., Results: The average age of SOTRs at time of tumor presentation was younger than typically seen in immunocompetent patients for AFX. Rates of local recurrences and metastases were higher in the SOTRs than is noted in the immunocompetent literature. Rates of recurrence were higher in those treated with excision than in those treated with Mohs micrographic surgery (MMS)., Conclusion: AFX and UPS may have a greater risk for recurrence, metastases, and mortality in SOTRs, in whom early treatment with MMS may demonstrate certain advantages in terms of minimizing risk of recurrence and metastasis. UPS and recurrent tumors should be staged appropriately and may respond to adjuvant radiation therapy and reduction of immunosuppression. Immunohistochemical evaluation is recommended to exclude other spindle cell tumors., (© 2011 by the American Society for Dermatologic Surgery, Inc. Published by Wiley Periodicals, Inc.)

Malignant fibrous histiocytoma (MFH) of the bone is an aggressive tumor with high rates of local recurrence and metastasis. The development of novel therapeutic approaches is critical to improve the prognosis of patients with MFH. We reported previously that the side population (SP) cells of the MFH2003 bone MFH cell line have the characteristics of cancer stem-like cells (CSC)/cancer-initiating cells. In the present study, to establish immunotherapy targeting CSC, we analyzed cell surface immune molecules on SP cells of the MHF2003 cell line, as well as autologous CTL responses against these SP cells in the tumor microenvironment and peripheral circulating lymphocytes, using autologous tumor-infiltrating lymphocytes and autologous CTL clones derived from peripheral blood, respectively. We found that the SP cells expressed human leukocyte antigen (HLA) Class I molecules on the cell surface. The autologous tumor-infiltrating lymphocyte line TIL2003 recognized both the SP and main population cells of the MFH2003 cell line. Next, we induced the CTL clone Tc4C-6 by mixed lymphocyte tumor cell culture using autologous peripheral blood mononuclear cells and freshly isolated SP cells, followed by a limiting dilution procedure. The Tc4C-6 clone showed specific cytotoxicity against the SP cells. Moreover, the cytotoxicity against SP cells was blocked by the anti-HLA Class I antibody W6/32. In conclusion, the findings of the present study support the idea that CSC of bone MFH are recognized by autologous CTL in the tumor microenvironment and peripheral circulating lymphocytes. Thus, CTL-based immunotherapy could target CSC of bone sarcoma to help prevent tumor recurrence., (© 2011 Japanese Cancer Association.)

Background: Abnormalities in the expression of human leucocyte antigens (HLA) by tumour cells impair cellular immune responses promoting immune evasion and tumour survival. To date, studies analysing HLA class I and class II expression levels in malignant fibrous histiocytomas, fibrosarcomas and dermatofibrosarcoma protuberans are limited., Aims: Therefore, we investigated the in vivo expression profile of HLA class I and class II antigens in 99 malignant fibrous histiocytomas, 20 fibrosarcomas and 34 dermatofibrosarcoma protuberans from different anatomical sites., Material and Methods: Immunohistochemistry using monoclonal antibodies to HLA class I and class II antigens was used to define the expression levels of these antigens on respective tumour samples., Results: Frequent loss or downregulation of HLA class I and class II expression in malignant fibrous tumours was observed for the different types of tumours examined., Discussion: The data presented suggest for the first time a high frequency of HLA class I and class II abnormalities in malignant fibrous histiocytomas, fibrosarcomas and dermatofibrosarcoma protuberans in vivo., Conclusion: This information might be useful in the practical and clinical design of tumour vaccination strategies., (© 2010 The Authors. Journal of the European Academy of Dermatology and Venereology © 2010 European Academy of Dermatology and Venereology.)

We report a case of multiple dermatofibromas in a patient with systemic lupus erythematosus (SLE) and Sjögren's syndrome. He was treated with prednisolone, diaphenylsulfone, and cyclosporine for SLE. He noticed two brown nodules on his right lower leg 3 years after the first consultation. Subsequently, six nodules developed within 6 months, and 2 more nodules after 10 months. Histopathological examination of a nodule on his left hand showed fibrotic proliferation with a storiform pattern in the whole dermis, but neither necrosis nor mitosis was observed. From these findings, a diagnosis of multiple dermatofibromas was made. As these tumors appeared during the remission stage of SLE, they might have been under immunosuppressive conditions caused by immunosuppressing agents rather than collagen disease itself.

Towards the goal of identifying tumor-rejection antigens on eradicated tumors in bone and soft tissue sarcomas, we evaluated the immune response against antigens presented by lost HLA class I molecules. Tumor specimens and peripheral blood samples were obtained from a 70-year-old woman with pleomorphic malignant fibrous histiocytoma. Over 1-year culture, a tumor cell line (MFH2004) was established. A B-cell line infected with Epstein-Barr virus (B2004-EBV) was developed from the blood samples. HLA genotypes of B2004-EBVcells were A*0206/2402, B*4006/4601, and C*0102/0801, whereas MFH2004 cells were defective for A*0206, B*4006, and C*0102. Loss of HLA-A2 expression was also proved immunohistochemically in the primary tumor tissues. Lost HLA-A2 in MFH2004 cells was retrieved by transfection of HLA-A*0206 cDNA to develop MFH2004-A2. Attempts to induce CTLs by mixed culture with autologous T cells and MFH2004 cells resulted in failure. In contrast, those with MFH2004-A2 induced CTL clones CTL2004-c6 and CTL2004-c17. These CTL clones specifically killed MFH2004-A2 but not MFH2004 or B2004-EBV in an HLA-A2-restricted manner. These findings suggest that CTL2004-c6 and CTL2004-c17 recognize autologous tumor-rejection antigens presented by HLA-A*0206, which may have been expressed by tumor cells that had been eradicated by the host's immunosurveillance system., ((c) 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.)

Atypical fibroxanthoma (AFX), a benign lesion, and pleomorphic malignant fibrous histiocytoma (MFH) are thought to represent points along the same neoplastic spectrum but with different prognoses and treatments. Diagnosis based on histology and clinical parameters alone is sometimes difficult, and a reliable cost-effective immunohistochemical marker to help distinguish these lesions would be beneficial. The diagnosis of AFX or MFH was based upon published clinical and microscopic criteria. Formalin-fixed, paraffin-embedded tissues of 17 cases of AFX and 26 cases of MFH were immunostained with monoclonal antibody to CD99. For all cases, CD99 expression was scored on a four-tiered scale: negative, weak (1+), moderate (2+), or strong (3+). Two pathologists blinded to tumor diagnoses and type of immunostain evaluated each case independently. The interobserver correlation coefficient was calculated. Seventeen patients with AFX (16 males and one female; mean age = 79) and 26 patients with MFH (16 males and 10 females; mean age = 60) were included. AFX lesions were from the head and the face, mean size = 1.5 cm, and MFH lesions were from the head, the neck, the trunk, and the upper/lower extremities, mean size = 5.2 cm. The 17 cases of AFX demonstrated moderate or strong (2 to 3+) immunoreactivity with CD99, compared to nine of 26 (35%) MFH cases (chi-square = 18.38; p < 0.001; interobserver correlation coefficient = 0.83). Of these, 16 of 17 (94%) AFX cases stained diffusely with CD99, while only four of 26 (15%) MFH cases stained diffusely. Control slides were adequate. Our study demonstrated that CD99 can help distinguish AFX from MFH, in addition to other immunohistochemistry as well as clinical and histologic criteria.

Aims: We report herein an additional case of primary malignant fibrous histiocytoma (MFH) in the duodenum and provide a review of the existing literature., Methods and Results: A 61-yr-old Chinese man was admitted to our hospital with symptoms of melena, anorexia, and weight loss. An abdominal computed tomography (CT) and gastrointestinal barium meal examination demonstrated a tumor of the duodenum suggestive of primary malignancy. The tumor was successfully treated by pancreaticoduodenectomy. It was histopathologically and immunohistochemically diagnosed to be a storiform-type primary MFH of the duodenum. There have been a total of 40 cases of primary malignant fibrous histiocytoma of the small bowel documented in the literature including our Chinese cases., Conclusion: Primary malignant fibrous histiocytoma of the small bowel, especially in the duodenum is extremely rare. The final diagnosis is made only after pathological and immunopathological examination of the tumor. The malignant potential of such tumors is high. The prognosis may be mainly dependent on the invasion and metastasis of tumor, while tumor size is irrelevant. The treatment should be surgery if possible. Early surgical intervention may be the best form of management that may offer the patient good result.