Ossifying epithelioid hemangioendothelioma

Lymphangiosarcoma with bone formation of the auricle in a dog

A 12-year-old mixed-breed neutered female dog was referred with cutaneous tumors at the left auricle. Histologically, the cutaneous tumor located in the dermis comprised numerous clefts and cavernous channels lined by neoplastic endothelial cells with no erythrocytes. Bone tissue without direct contact with neoplastic cells was seen in the well-developed stromal connective tissue. The neoplastic endothelial cells exhibited mild to moderate atypia. Immunohistochemically, neoplastic cells were positive for vimentin and negative for cytokeratin and factor VIII-related antigen. Basement membrane around the neoplastic lumens was positive for laminin in a linear or granular pattern. Ultrastructural examination revealed discontinuous basement membrane beneath the tumor cells. Histopathological features of this case were consistent with lymphangiosarcoma, and stromal ossification was characteristic.

Hemangioendothelioma

Hemangioendothelioma is the term used to name those vascular neoplasms that show a borderline biological behavior, intermediate between entirely benign hemangiomas and highly malignant angiosarcomas. Although originally spindle cell hemangioendothelioma was proposed as a specific clinicopathologic variant of hemangioendothelioma, currently, it is considered as an entirely benign lesion, and thus, the name spindle cell hemangioma seems to be the most accurate for this lesion. Authentic hemangioendotheliomas involving the skin and soft tissues include papillary intralymphatic angioendothelioma (also known as Dabska tumor), retiform hemangioendothelioma, kaposiform hemangioendothelioma, epithelioid hemangioendothelioma, pseudomyogenic hemangioendothelioma (also known as epithelioid sarcoma-like hemangioendothelioma), and composite hemangioendothelioma. Each of these neoplasms exhibit characteristic histopathologic features. The most characteristic finding of papillary intralymphatic hemangioendothelioma consists of papillary tufts, with a central hyaline core lined by hobnail-like endothelial cells protruding into the lumina. Retiform hemangioendothelioma is an infiltrative neoplasm composed of elongated arborizing vessels, arranged in an anastomosing pattern that resembles that of the rete testis, and lined by a single layer of hobnail-like endothelial cells that protrude within the narrow lumina. Kaposiform hemangioendothelioma is composed of several solid poorly circumscribed nodules, and each nodule is composed of a mixture of small capillaries and solid lobules of endothelial cells arranged in a glomeruloid pattern. A frequent finding consists of the presence of areas of lymphangiomatosis adjacent to the solid nodules. Epithelioid hemangioendothelioma is composed of cords, strands, and solid aggregates of round, oval, and polygonal cells, with abundant pale eosinophilic cytoplasm, vesicular nuclei, and inconspicuous nucleoli, embedded in a fibromyxoid or sclerotic stroma. Many neoplastic cells exhibit prominent cytoplasmic vacuolization as an expression of primitive vascular differentiation. Pseudomyogenic hemangioendothelioma is a poorly circumscribed, fascicular lesion with infiltrative borders composed of round or oval neoplastic cells, with vesicular nuclei and inconspicuous nucleoli, and ample homogeneous eosinophilic cytoplasm, giving them a rhabdomyoblastic appearance. Finally, composite hemangioendothelioma is the term used to name locally aggressive vascular neoplasms of low-grade malignancy showing varying combinations of benign, low-grade malignant, and high-grade malignant vascular components. From the immunohistochemical point of view, proliferating cells of all hemangioendotheliomas express a lymphatic endothelial cell immunophenotype. Most hemangioendotheliomas are low-grade vascular neoplasms, with a tendency to recur locally and a low metastatic potential, mostly to regional lymph nodes. Epithelioid hemangioendothelioma, especially large lesions and those located in deep soft tissues, seems to have a more aggressive biological behavior.

Fibroma with osseous metaplasia of external auditory canal in a dog

The present report describes a case of fibroma with osseous metaplasia of the external auditory canal in a 7-year-old male Pomeranian dog. Upon otoscopic examination, the right external auditory canal was almost completely obstructed by a well-circumscribed mass adjacent to the eardrum. The mass was surgically excised. Grossly, it was well demarcated, firm when cut, pink, and measured 0.3 cm x 0.2 cm x 0.7 cm. The cut surface of the mass exhibited a central portion of homogeneously white osseous components surrounded by brown to pink soft tissue. Microscopically, the resected external auditory canal mass mainly consisted of fibroblastic spindle cells showing differentiation to metaplastic osteoblast-like cells. Metaplastic osteoblasts and osteoclasts lining the osteoid bony trabeculae were also observed. Bony trabeculae and spicules were separated by abundant collagen and neoplastic fibroblastic cells. Fibromatous components, irregular formation of woven bone spicules, and the presence of osteoblasts lining bony trabeculae led to a diagnosis of fibroma with osseous metaplasia.

Angiomatosis: a case with metaplastic ossification

Angiomatosis is defined as a hemangioma that affects a large segment of the body in a contiguous fashion, either by vertical extension to involve multiple tissue planes (eg, skin, subcutis, muscle, bone) or by crossing muscle compartments to involve similar tissue types (eg, multiple muscles). Such lesions usually present in the first 2 decades of life and have a highly characteristic but not totally specific histological pattern. Histology usually shows a haphazard mixture of small and medium-sized vessels, fat, connective tissue, and lymphatics. Large amounts of mature fat frequently accompany the vascular elements, suggesting that the lesion may possibly be a more generalized mesenchymal proliferation rather than an exclusively vascular lesion. Here we present what we believe to be the first case of angiomatosis showing osseous metaplasia.

Epithelioid hemangioendothelioma of the head and neck: role of podoplanin in the differential diagnosis

Epithelioid hemangioendothelioma is an uncommon vascular tumor of soft tissue and bone that may rarely occur in the liver, lung and the head and neck. We present five new cases of epithelioid hemangioendothelioma of the head and neck region diagnosed and managed in one institution in order to define the phenotypic characteristics, podoplanin immunohistochemical staining and the biological outcome. Podoplanin is a transmembrane mucoprotein selectively expressed in lymphatic endothelium and recently in some vascular neoplasms. The patients were comprised of two male and three female patients ranging in age from 4 to 71 years. The lesions were found in the gingiva, submandibular region soft tissue, nasal cavity and tongue, and ranged in size from 0.7 to 2.5 cm. All tumors manifested infiltrative cords and nests of epithelioid cells with occasional spindle morphology in a myxoid stroma. Immunohistochemical analysis of vascular and epithelial markers showed strong and uniform cytoplasmic reactivity for podoplanin and variable intensity and staining of CD31 and lack of cytokeratin staining in tumor cells. Surgical treatment included simple and wide local excisions. Of the three patients with follow-up, one developed lymph node metastasis and one had no evidence of disease 10 months after surgery. The patient with multiple recurrences and LN metastases was additionally treated with chemotherapy and is under consideration for radiation therapy. Hemangioendothelioma of the head and neck is: (1) a low-grade malignancy with a tendency for local recurrence and regional lymph node metastasis, (2) complete excision with negative margins is the treatment of choice for localized disease and (3) podoplanin may be useful in differentiating epithelioid hemangioendothelioma from non-vascular tumors.

Vascular tumors of the skin: A selective review

Cutaneous vascular proliferations are a vast and complex spectrum. Many appear as hamartomas in infancy; others are acquired neoplasms. Some vascular proliferations are hyperplastic in nature, although they mimic hemangiomas, i.e., neoplasms. The vast majority of the vascular lesions are hemangiomas. Between the hemangiomas and frankly angiosarcomas, there is a group of neoplasms that are angiosarcomas, albeit ones of low grade histologically and, probably, biologically. The term "hemangioendothelioma" has been created to encompass these neoplasms. Vascular proliferations are, fundamentally, composed of endothelial cells. Some hemangiomas, however, contain also abundant pericytic, smooth muscle, or interstitial components, or a combination of them. These heterogeneous cellular components are present usually in hemangiomas. Some of the newly described vascular proliferations, however, are difficult to differentiate from some of the angiosarcomas. Others are markers, occasionally, of serious conditions such as Fabry's Disease (angiokeratoma) and POEM's syndrome (glomeruloid hemangioma). Kaposi's sarcoma continues to be an enigma. The demonstration of Herpes virus 8 in this condition raises doubt about its neoplastic nature. The demonstration of endothelial differentiation of its nodular lesions is tenuous and its true nature remains unresolved. While physicians have known about post-mastectomy angiosarcomas from the origin of the radical mastectomy, a new group of unusual vascular proliferations of the mammary skin are being defined. These lesions arise in the setting of breast-conserving surgical treatment with adjuvant radiation therapy. The incubation period is usually 3 to 5 years, in contrast with the 10, or more, in classical cases of post-mastectomy angiosarcoma. These lesions usually are subtle, both clinically and histologically, in contrast with the "classical," dramatic presentation of mammary angiosarcoma. The spectrum of findings ranges from "simple" lymphangiectasia-like vascular proliferations to unequivocal angiosarcomas. The pathogenesis of these lesions remains a mystery. There are very few clues that allow one to separate hemangiomas from angiosarcomas. The presence of heterologous cellular elements and, particularly, well-developed smooth muscle components tends to favor a hemangioma. Similarly, the presence of thrombosis usually supports hemangioma. Nevertheless, there are no unequivocal or reliable individual diagnostic criteria. A thorough knowledge of the different conditions and their differential diagnoses eventually leads to the proper diagnosis in most cases.

Selected cutaneous vascular neoplasms. A review

This article reviews the pathology of benign, borderline, and malignant vascular neoplasms of the skin. The classification of vascular lesions of childhood is presented. Defined variants of hemangioma (including sinusoidal, microvenular, glomeruloid, epithelioid, and targetoid hemosideric hemangioma, as well as acquired tufted hemangioma and angiofibroma) are discussed. Borderline hemangioendotheliomas are classified. Kaposi sarcoma is reviewed with an update on the role of human herpesvirus type 8 in its pathogenesis. Angiosarcoma and acquired progressive lymph-angioma are also discussed.

Basal cell carcinoma with massive ossification

We report a case of basal cell carcinoma with massive ossification in a 66-year-old white man. Ossification in various benign and malignant neoplasms have been reported including basal cell carcinomas, in which ossifications are seen in small foci or peripheral rim of the tumor. However, in our case, massive ossification is seen throughout the tumor, and only small areas of the periphery of the tumor show diagnostic histology. Therefore, this case might have presented a diagnostic difficulty or been misdiagnosed as an osteoma cutis if a smaller incisional or punch biopsy had been performed. The phenomenon of bone formation itself is not specific for any diagnostic entity, and therefore an underlying lesion should be carefully sought in case of secondary ossification.

Epithelioid hemangioendothelioma presenting in the skin: a clinicopathologic study of eight cases

Epithelioid hemangioendothelioma arising in the skin is extremely rare, and the majority of documented cases have developed in association with an underlying bone tumor. We report eight patients with an age range of 29-84 years (mean 53), who presented with primary cutaneous tumors at a variety of sites including the palm, shin, neck, knee, nose, back, and penis with a duration of between 6 and 12 months. Histologically, all eight cases presented as circumscribed nodules with an overlying acanthotic epidermis, three showing striking acrosyringeal proliferation, reminiscent of eccrine syringofibroadenoma. The tumors were composed of an admixture of slightly pleomorphic spindle and epithelioid cells with abundant, sharply defined eosinophilic cytoplasm and vesicular nuclei containing single nucleoli. Mitoses were generally sparse. All tumors showed intracytoplasmic lumina and intraluminal erythrocytes were occasionally apparent. The tumor cells were embedded in a myxoid or hyaline matrix. In contrast to visceral lesions, a vascular origin was not evident in any of our cases. The tumor cells variably expressed CD31, CD34, factor VIII-Rag, and smooth-muscle actin but not pankeratin or epithelial membrane antigen. Follow-up ranged from 4 months to 3 years. None of the lesions has thus far recurred and there have been no metastases.