UNASSIGNED: Vascular malignancies are categorized into benign hemangiomas, malignant angiosarcomas, and tumors of intermediate malignancy. Retiform hemangioendothelioma (RH) is one of the rare diagnoses belonging to the class of intermediate malignancies that was initially diagnosed.
UNASSIGNED: In this case report, we have reported a rare case of RH, a locally aggressive, vascular tumor of malignant potential presenting at an unusual site. The most observed locations of this soft tissue tumor are skin and subcutaneous tissues of extremities; however, this case of RH was observed in an unusual site called pleura, which is a rare occurrence related to this tumor. The presence of cell surface markers like CD31 and ERG of vascular and endothelial origin and the presence of hobnail appearance of endothelial channels on the biopsy profile supported the vascular origin of the tumor; the clinical features and imaging studies further confirmed the diagnosis of RH.
UNASSIGNED: In this case report, a rare case of RH with an unusual site of origin was highlighted. RH is a vascular neoplasm; commonly observed sites of this vascular tumor were skin and subcutaneous tissue of the extremities; however, in this case, the site was unusually different, which was the pleura of the left lung.

Retiform hemangioendothelioma (RH) is a rare intermediate (locally aggressive) vascular tumor that mostly affects the dermis of the trunk and limbs, but has never been reported in the inferior turbinate. A 10-year-old Chinese boy presented with recurrent epistaxis in his left nasal cavity and anemia for more than 2 years. Radiographic and electronic video laryngoscopic images showed an expansile mass in the left inferior turbinate. Endoscopic surgery and electrocautery were performed to resect the tumor beyond the macroscopic border. Histopathologically, the tissues were infiltrated by hyperplastic blood vessels arranged in a retiform pattern, and endothelial cells proliferate significantly in some areas. Immunohistochemistry showed a positive result for CD31, CD34, Fli-1, and ERG. No epistaxis, tumor recurrence, or metastasis was found on reexamination over 18 months after surgery.

UNASSIGNED: Composite hemangioendothelioma (CHE) is a rare, locally aggressive neoplasm of intermediate malignant potential. It is composed of a mixture of vascular tumors with a predilection for the dermis and subcutis of the extremities.
UNASSIGNED: In this report, we describe a 41-year-old man who presented with a 2-month history of headache, dizziness, and intermittent seizures. Magnetic resonance imaging showed a hemorrhagic, multilobulated, and dural-based mass with extension into the calvarium. The mass measured 10.3 × 4.8 × 4 cm along the interhemispheric fissure and encased the superior sagittal sinus. Excision was performed, and histopathologic examination revealed a heterogeneous mixture of vascular components consisting of epithelioid hemangioendothelioma, retiform hemangioendothelioma, and hemangioma. This is the first report of a primary intracranial CHE.
UNASSIGNED: The spectrum of mesenchymal neoplasms within the cranium expands to encompass CHE.

The term \"hemangioendothelioma\" is used for endothelial neoplasms of intermediate malignancy and describes a group of rare neoplasms having biologic behavior falling in between that of the benign hemangiomas and fully malignant angiosarcomas. The hemangioendotheliomas fall into several specific, clinicopathologically and genetically distinct entities, specifically epithelioid hemangioendothelioma, kaposiform hemangioendothelioma, papillary intralymphatic angioendothelioma and retiform hemangioendothelioma (hobnailed hemangioendothelioma), pseudomyogenic hemangioendothelioma, composite hemangioendothelioma, and YAP1::TFE3-fused hemangioendothelioma. The clinical, morphologic, immunohistochemical, and genetic features, and the differential diagnosis of each of these rare entities are discussed in this review.

BACKGROUND: Retiform hemangioendothelioma (RH) is a rare, intermediate-grade vascular tumor that often arises in the trunk and extremities. The clinical and radiological features of RH remain largely unknown.
METHODS: A male patient in his 70s presented with shortness of breath on exertion, and computed tomography incidentally revealed a tumor in his right breast. Positron emission tomography (PET) revealed moderate 18F-fluorodeoxyglucose (FDG) uptake in the tumor. RH was observed in the resected specimens. Three months after surgery, the patient was free of local recurrence and distant metastasis.
CONCLUSIONS: RH was found in the male breast and was accompanied by FDG uptake on PET. PET may be useful in diagnosing RH. Although metastasis is rare in RH, local recurrence may occur, and careful follow-up is required.

Retiform hemangioendothelioma (RH) is a rare vascular neoplasm with intermediate malignant potential mostly occurring in extremities. It is important to differentiate this neoplasm from malignant conditions as RH has a good prognosis. As it has a tendency to recur locally, it may be misdiagnosed as a malignant tumor. Herein, we report a rare case of RH occurring in the medial canthus.

Retiform hemangioendothelioma (RH) is a rare borderline-malignant vascular tumor with specific histological characteristics, usually occurring in the limbs and trunk. We report the case of a 63-year-old woman who presented with a painless, oval nodule that had been growing slowly on her left vulva for 3 years. Magnetic resonance imaging of the pelvic cavity revealed a 4.4- × 2.7- × 1.8-cm cystic lesion in the subcutaneous fat of the left vulva. Resection beyond the macroscopic border was performed. Pathology revealed vascular structures with elongated and narrow arborizing vascular channels that were arranged in a retiform pattern resembling rete testis tissue. Immunohistochemical endothelial staining was positive for CD31, CD34, and Friend leukemia integration-1 (FLI-1). The above features confirmed a diagnosis of RH. There was no local recurrence or metastasis during the 26-month follow-up. RH of the vulva is rare, and its diagnosis is supported by specific histological characteristics and immunohistochemical staining for CD31, CD34, and FLI-1. Wide surgical resection with tumor-free margins is important for a favorable prognosis.

Composite hemangioendothelioma is a rare vascular tumor morphologically comprising several distinct vascular components and exhibits a borderline malignant potential. We described the case of a 53-year-old female who presented with an infiltrative mass in the paravertebral soft tissue. The tumor showed discrete nests of synaptophysin-expressing epithelioid cells accompanied by rich vasculature, features highly reminiscent of sympathetic paraganglioma. Further analysis revealed areas resembling spindle cell hemangioma, retiform hemangioendothelioma, cavernous hemangioma/lymphangioma, and epithelioid hemangioendothelioma without the myxohyaline matrix in the tumor, and a final diagnosis of composite hemangioendothelioma with synaptophysin expression was made. Critical appraisal of this recently described entity and its possible pathogenic relationship with retiform hemangioendothelioma were discussed.

Retiform hemangioendothelioma is a rare vascular neoplasm of intermediate grade, the diagnosis of which can be challenging. We report a case of 35-year-old man with swelling in the postauricular region. He had undergone FNAC which had revealed blood only. Microscopic examination showed narrow, arborizing, vascular channels resembling normal rete testis. Evidence of mitoses or cytological atypia were lacking. Immunohistochemistry showed diffuse and strong staining for CD34 along with CD31 positivity. Immunostains for D240 and GLUT1 were negative. A diagnosis of retiform hemangioendothelioma was made. Histologically, it should be distinguished from Kaposiform hemangioendothelioma, Dabska tumor, epithelioid hemangioendothelioma, and angiosarcoma.

Retiform hemangioendothelioma is a locally aggressive, rarely metastasizing, low-grade angiosarcoma characterized by intercommunicating vascular channels lined by hobnail or cuboidal endothelial cells, flanked by lymphocyte and hyaline sclerosis. Neoplastic endothelial cells usually express von Willebrand factor, CD31 and CD34, while the lymphocytic infiltrate shows a mixture of CD3+, T and CD20+ B cells. The authors describe a case of a 76-year-old female who presented with a soft, painless, ill-defined mass measuring 9 cm in her right gluteal region for the past 15 years, clinically suggestive of a lipoma. There was no regional lymphadenopathy. The mass was resected and sent for histopathological examination. The slow-growing lesion and the typical histomorphology led to the diagnosis of retiform hemangioendothelioma. The diagnosis was confirmed by immunohistochemistry using CD34 antibody, which strongly stained the endothelial cells. The patient was followed up for 6 months after the surgery and no recurrence was noted.