A simple Baker's cyst? Tocilizumab remits paraneoplastic signs and controls growth of IL-6-producing angiomatoid malignant fibrous histiocytoma

Modeling Extraordinary Response Through Targeting Secondary Alterations in Fusion-Associated Sarcoma

PURPOSE

Targeted therapy in translocation-associated sarcomas has been limited to oncogenic activation of tyrosine kinases or ligands while gene fusions resulting in aberrant expression of transcription factors have been notoriously difficult to target. Moreover, secondary genetic alterations in sarcomas driven by translocations are uncommon, comprising mostly alterations in tumor suppressor genes (TP53, CDKN2A/B). Our study was triggered by an index patient showing a dramatic clinical response by targeting the secondary BRAF V600E mutation in a metastatic angiomatoid fibrous histiocytoma (AFH) harboring the typical EWSR1::CREB1 fusion.

MATERIALS AND METHODS

The patient, a 28-year-old female, was diagnosed with an AFH of the thigh and followed a highly aggressive clinical course, with rapid multifocal local recurrence within a year and widespread distant metastases (adrenal, bone, liver, lung). The tumor showed characteristic morphologic features, with histiocytoid cells intermixed with hemorrhagic cystic spaces and lymphoid aggregates. In addition to the pathognomonic EWSR1::CREB1 fusion, targeted DNA sequencing revealed in both primary and adrenal metastatic sites a hot spot BRAF V600E mutation and a CDKN2A/B deletion. Accordingly, the patient was treated with a BRAF-MEK inhibitor combination (encorafenib/binimetinib) showing an excellent but short-lived response.

RESULTS

Using a CRISPR-Cas9 approach, we introduced the BRAF c.1799 T>A point mutation in human embryonic stem (hES) cells harboring a conditional EWSR1 (exon7)::CREB1 (exon7) translocation and further differentiated to mesenchymal progenitors (hES-MP) before fusion expression. The cells maintained the fusion transcript expression and the AFH core gene signature while responding to treatment with encorafenib and binimetinib.

CONCLUSION

These results highlight that additional targeted DNA NGS in chemotherapy-resistant translocation-associated sarcomas may reveal actionable oncogenic drivers occurring as secondary genetic events during disease progression.

Evidence of Chemoresponsiveness in Unresectable Metastatic Angiomatoid Fibrous Histiocytoma

Angiomatoid fibrous histiocytoma (AFH) is a soft tissue neoplasm of intermediate biological potential. Typically a slow-growing tumor, it can recur locally. Rarely, it manifests as a soft tissue sarcoma capable of metastasis. When metastases are nonamenable to local therapy, it is believed uniformly fatal. We present 3 patients with metastatic AFH who demonstrated a sustained response to chemotherapy; including one who achieved complete remission with cryoablation. These cases reinforce the potential value of chemotherapy in some patients with unresectable metastatic AFH and provide the first case in the literature of cryoablation in AFH.

Tocilizumab Controls Paraneoplastic Inflammatory Syndrome but Does Not Suppress Tumor Growth of Angiomatoid Fibrous Histiocytoma

Angiomatoid fibrous histiocytoma (AFH) is a rare soft tissue tumor that rarely metastasizes but lacks effective systemic therapy once it propagates. In some reports, high interleukin-6 (IL-6) production promotes tumor growth by autocrine stimulation and tocilizumab, an IL-6 receptor antagonist, can control AFH growth. Here, we present a case report on a patient with local recurrence and distant lymph node metastasis of AFH treated with tocilizumab. As a result, the inhibition of the IL-6 signaling pathway controlled paraneoplastic inflammatory syndrome (PIS); however, the local recurrent tumor progressed. This case implied that IL-6 is not necessarily the cause of tumor growth in AFH. Therefore, physicians should bear in mind that watchful observation is needed whether tocilizumab can control tumor progression despite the amelioration of PIS associated with the attenuated effect of IL-6 on AFH.

Cytokeratin-positive Malignant Tumor in the Abdomen With EWSR1/FUS-CREB Fusion: A Clinicopathologic Study of 8 Cases

ATF1, CREB1, and CREM, which encode the CREB family of transcription factors, are fused with EWSR1 or FUS in human neoplasms, such as angiomatoid fibrous histiocytoma. EWSR1/FUS-CREB fusions have recently been reported in a group of malignant epithelioid tumors with a predilection to the peritoneal cavity and frequent cytokeratin expression. Here, we studied 8 cytokeratin-positive abdominal malignancies with these fusions for further characterization. The tumors affected males (15 to 76 y old) and presented as intra-abdominal masses with concurrent or subsequent peritoneal dissemination, ascites, and/or metastases to the liver or lymph nodes. Four patients died of the disease within 18 to 140 months. Cases 1 to 5 showed multinodular growth of monomorphic epithelioid cells with focal serous cysts. Lymphoplasmacytic infiltration was prominent and was associated with systemic inflammatory symptoms. Two patients suffered from membranous nephropathy with nephrosis. The tumors displayed partly overlapping phenotypes with malignant mesothelioma, including diffuse strong expression of AE1/AE3 and WT1 and membranous positivity of sialylated HEG1, although calretinin was negative. Case 6 showed similar histology to cases 1 to 5, but expressed smooth muscle actin diffusely, lacked WT1 and HEG1, and harbored prominent pseudoangiomatous spaces. Cases 7 and 8 displayed dense growth of small oval to short spindle cells, with occasional molding and minor swirling, superficially resembling small cell carcinoma. Lymphoplasmacytic infiltration was not observed. The tumors were positive for AE1/AE3 and CD34 (focal), whereas calretinin, WT1, and HEG1 were negative. The detected fusions were FUS-CREM (n=4), EWSR1-ATF1 (n=2), EWSR1-CREB1 (n=1), and EWSR1-CREM (n=1). We confirmed the prior observation that these tumors do not fit perfectly with known entities and provided additional novel clinicopathologic information. The tumors require wider recognition because of more aggressive behavior than angiomatoid fibrous histiocytoma despite similar genetics, and potential misdiagnosis as unrelated diseases, such as neuroendocrine neoplasms.

Cranial angiomatoid fibrous histiocytoma: A case report and review of literature

Background:

Angiomatoid fibrous histiocytoma (AFH) is a rare low-grade soft-tissue tumor that typically arises from the deep dermal and subcutaneous tissue of the extremities in children and young adults. Intracranial AFH is exceedingly rare, and only four cases of primary AFH tumors have been reported to date.

Case Description:

A 43-year-old male presented to our hospital with headaches, vision changes, and a known brain tumor suspected to be an atypical meningioma. After undergoing craniotomy for resection of the mass, the immunomorphologic features of the resected tumor showed typical features of AFH with ESWR1 (exon7) – ATF1 (exon 5) fusion.

Conclusion:

AFH is a difficult tumor to diagnose with imaging and histologic studies. Thus, further knowledge is necessary – particularly of intracranial cases – to aid clinicians in its diagnosis and management.

Paraneoplastic disorders associated with miscellaneous neoplasms with focus on selected soft tissue and Undifferentiated/ rhabdoid malignancies

A variety of soft tissue and visceral neoplasms have been associated with constitutional symptoms and signs including fever, fatigue, arthritis and laboratory abnormalities such as elevated erythrocyte sedimentation rate, leukocytosis with marked neutrophilia, anemia, thrombocytosis and others. This review addresses three main neoplastic categories that are associated with specific paraneoplastic phenomena: (1) neoplasms having in common the presence of diffuse mixed inflammatory infiltration (closely simulating an inflammatory pseudotumor) and frequently associated with constitutional symptoms; (2) neoplasms with undifferentiated, anaplastic or rhabdoid cell morphology (frequently SWI/SNF-deficient) associated with diverse paraneoplastic manifestations; and (3) paraneoplasia associated with neoplasms carrying specific gene fusions such as solitary fibrous tumor (STAT6-NAB2 gene fusions), infantile fibrosarcoma and congenital mesoblastic nephroma (ETV6-NTRK3 gene fusions), and angiomatoid fibrous histiocytoma (EWSR1-CREB1 & EWSR1-ATF1 fusions).

Therapeutic response of metastatic angiomatoid fibrous histiocytoma carrying EWSR1-CREB1 fusion to the interleukin-6 receptor antibody tocilizumab

Angiomatoid fibrous histiocytoma (AFH) is a rare soft tissue tumor that has been associated with EWSR1-CREB1 gene fusion. Outcome in patients with unresectable distant metastases is generally fatal. Interleukin-6 (IL-6) secretion has been described in tumors with EWSR1-CREB1 fusion, and may promote tumor growth due to autocrine stimulation. Tocilizumab is an IL-6 receptor antibody that has potential benefit as a targeted therapy in refractory neoplasms with IL-6 secretion. We describe a child with metastatic AFH with EWSR1-CREB1 fusion and elevated IL-6 whose disease progressed during treatment with traditional chemotherapeutic agents, but improved after targeted therapy with tocilizumab.