Angiofibroblastoma of the skin: a report of seven cases in support of a distinctive entity.

BACKGROUND: Angiofibroblastoma of the skin is a recently described benign tumor with fibroblastic differentiation. The tumor is composed of stellate and spindle fibroblasts embedded in a fibromyxoid and fibrous matrix that contains numerous capillary-sized blood vessels. METHODS: All cases of fibromyxoid tumors of the skin from the files of two dermatopathologic centers and from consultation cases, together with clinical data and histopathologic specimens, were reviewed. Additionally, immunohistochemical studies were performed in all cases. RESULTS: Seven cases of angiofibroblastoma of the skin were found, including two cases previously reported. All cases showed similar histopathologic findings. The morphologic versatility of fibroblasts, however, explains some of the microscopic variations that were observed in three cases of this series. Immunohistochemical studies support the fibroblastic nature of the neoplasms. CONCLUSIONS: Our series provides data suggesting that angiofibroblastoma of the skin represents a distinctive entity, which should be considered in the differential diagnosis of other fibromyxoid tumors of the skin.

Fibrous spindle cell lipoma: report of a new variant.

Spindle cell lipoma is a benign tumor characterized by mature fatty tissue alternating with short fascicles of small spindle cells in a stroma that varies from fibrous to myxoid. The variable proportion of these elements among different examples of the neoplasm confers to spindle cell lipoma a variable microscopic appearance that can make the diagnosis difficult. Furthermore, in some instances, spindle cell lipoma may resemble liposarcoma, hemangiopericytoma, neurilemmoma, and other neoplasms representing a histopathologic pitfall. We report on two cases of spindle cell lipoma with abundant fibrous stroma reminiscence of fibroma and fibrolipoma. The name fibrous spindle lipoma is proposed for this tumor.

"Tubular Spitz's nevus" an artifact of fixation?

BACKGROUND: Spitz's nevi may contain numerous tubule-like structures. This phenomenon has been described as "tubular Spitz's nevus" and has been attributed to either apoptosis in the center of nests of melanocytes or tubular metaplasia of melanocytes. METHODS: In order to study this peculiar phenomenon, we reviewed 31 Spitz's nevi from our teaching collection. RESULTS: Empty spaces vaguely resembling tubules were found in 15 Spitz's nevi, all of which were examples of the epithelioid-cell type of Spitz's nevus. Histopathologically and immunohistochemically, there was no evidence of apoptosis within or around tubule-like structures. Empty; spaces in the center of nests ranged from distinctive tubule-like structures to only slight separation of melanocytes from one another. Furthermore, empty spaces were also seen around nests, often in combination with distinctive tubule-like changes. CONCLUSIONS: Our findings suggest that so-called "tubular" structures in epithelioid Spitz's nevi result from retraction of tissue secondary to fixation in formalin. "Tubular Spitz's nevus" seems to represent an artifact rather than a distinctive variant of Spitz's nevus.

Palisading and verocay body-prominent dermatofibrosarcoma protuberans: a report of three cases.

UNLABELLED: The aim of this report is to draw attention to nuclear palisading and Verocay body formation as peculiar, previously undescribed histological findings in rare instances of dermatofibrosarcoma protuberans (DFSP). METHODS AND RESULTS: Three indurated, nodular or plaque skin lesions were diagnosed as DFSP on the basis of their storiform proliferation of spindle-shaped cells diffusely infiltrating the dermis and subcutaneous tissue. Sclerosing and giant cell areas were also identified. Unexpectedly, conspicuous nuclear palisading was also noted in all cases and Verocay body formation was present in two. Immunostains were positive for CD34 and negative for S100 protein in every instance. Proliferating cells were seen to display fibroblast-like features by ultrastructural study of one case. CONCLUSIONS: DFSP may rarely show a schwannoid histological appearance as the result of nuclear palisading and even Verocay body formation. In this setting, both the search for DFSP characteristic morphologic features and the performance of CD34 and S100 protein immunohistochemistry will facilitate the correct diagnosis.

Desmoplastic leiomyosarcoma of the skin.

This report focuses on two unusual cases of cutaneous leiomyosarcoma composed of sparse numbers of neoplastic cells embedded in abundant sclerotic stroma throughout the entire neoplasm. To the best of our knowledge, only one example of this rare lesion has been described previously as "sclerotic primary cutaneous leiomyosarcoma." However, the resemblance of this tumor to other desmoplastic tumors of the skin is striking and, therefore, we propose the term desmoplastic leiomyosarcoma of the skin for this neoplasm. Because of the sparse cellularity and the abundant stroma, desmoplastic leiomyosarcoma of the skin can be easily misinterpreted, especially in small biopsies. It should be included in the differential diagnosis of inflammatory skin diseases associated with sclerosis, such as radiation dermatitis, and of desmoplastic tumors of the skin, including desmoplastic melanocytic nevus, desmoplastic melanoma, and desmoplastic squamous cell carcinoma.

Angiomatoid Spitz nevus: a distinct variant of desmoplastic Spitz nevus with prominent vasculature.

Five cases of a distinctive variant of desmoplastic Spitz nevus are reported. To the best of our knowledge, this tumor has never been described previously. Clinically, it presents itself as a solitary papule on the extremities of young adults. Microscopically, it shows predominance of solitary melanocytes with epithelioid appearance over cell nests. They are embedded in a prominent fibrous stroma with many densely arranged, small blood vessels with plump endothelia not seen in other Spitz nevi. Because of its resemblance to a vascular tumor, the name angiomatoid Spitz nevus is proposed for this lesion. Absence of recurrences or metastases after complete excision in all cases supports the benign nature of the tumor.

Histopathologic diagnosis of superficial soft tissue tumors, related lesions, and simulators: an algorithmic approach based on colors: tumors with predominance of pink.

An algorithmic approach based on colors for histopathologic diagnosis of soft tissue tumors and their simulators is proposed. At scanning magnification, in specimens stained with hematoxylin and eosin, mesenchymal tumors can be classified according to their color. The color of a tumor is basically determined by density, morphology, and distribution of neoplastic cells, and by density and quantity of the stroma. The basic colors that can be observed by neoplasms stained with hematoxylin and eosin are white, pink, red, and blue. Colors may be used as a first step in choosing the algorithm for specific diagnosis of a given mesenchymal neoplasm. Furthermore, colors may be helpful in understanding the histogenesis of a tumor, and this is especially important in soft tissue pathology, because criteria for benignancy and malignancy vary according to the nature of the neoplasm. In this article, tumors with a predominance of pink are analyzed. Pink tumors are composed of cells with abundant eosinophilic cytoplasm and sparse chromatin in their nuclei, such as leiomyoma. In other cases, the pink color in a tumor is determined by abundant fibrous stroma rather than by characteristics of neoplastic cells, such as sclerotic fibroma.

Panniculitis: definition of terms and diagnostic strategy.

Inflammation of the subcutaneous tissue represents a dynamic process that shows different histopathologic findings at different stages of development; therefore, the stage of evolution of a lesion at the time of biopsy influences the microscopic appearance significantly. Furthermore, location and type of inflammation may vary among different examples of the same panniculitis independent of the stage of evolution. For these reasons, the histopathologic diagnosis of panniculitides is often difficult. Currently, the most common approach to diagnosis is differentiation between predominantly septal and predominantly lobular panniculitis, followed by the distinction between lesions with and without vasculitis. Although these criteria are important for diagnosis, they are often insufficiently specific. To determine an alternative method of diagnosis, 329 cases of panniculitis were histopathologically analyzed using the following parameters: location and type of inflammatory infiltrate within and around the subcutaneous tissue, presence or absence of fat necrosis, type of necrosis, presence or absence of vascular changes, and presence or absence of associated findings (e.g., hemorrhage, sclerosis). On the basis of the results of this study and of an extensive review of the literature, tables of histopathologic findings for the diagnosis of panniculitides are presented.

Insect bite-like reaction in patients with hematologic malignant neoplasms.

BACKGROUND: Exaggerated reaction to insect bites, mainly to mosquitoes, is infrequently described in patients with chronic lymphocytic leukemia. Skin lesions usually appear months to years after the diagnosis of leukemia and are unrelated to laboratory findings, disease course, or therapy. OBSERVATIONS: We describe 8 patients with various hematologic disorders (chronic lymphocytic leukemia, acute lymphoblastic leukemia, acute monocytic leukemia, mantle-cell lymphoma, large-cell lymphoma, and myelofibrosis) who developed insect bite-like reaction. Although the clinical picture and the histological characteristics of the lesions were typical for insect bites, none of the patients actually had a history, course, or response to treatment suggestive of arthropod assaults. In 2 patients, the eruption preceded the diagnosis of the malignant neoplasm. The rash persisted for months to years and was resistant to therapies other than systemic corticosteroids. The 3 patients with chronic lymphocytic leukemia seemed to have a worse prognosis than expected for their disease. In 1, the polymerase chain reaction detected leukemic cells in the infiltrate. CONCLUSIONS: Insect bite-like reaction is an infrequent, disturbing, and difficult-to-treat nonspecific phenomenon in patients with hematologic malignant neoplasms. Since it may precede the hematologic disorder, oriented evaluation is warranted. We speculate that immunodeficiency plays a role in its pathogenesis; however, the exact pathogenesis and its prognostic implications await further studies.

Benign lymphangiomatous papules of the skin following radiotherapy: a report of five new cases and review of the literature.

AIMS: The aim of this report is to summarize the clinicopathological findings of five cases of a pseudosarcomatous vascular proliferation of the skin at the site of radiotherapy following surgery for carcinoma of the breast and carcinoma of the endometrium. To our knowledge, only five cases of this presumably rare pseudomalignant proliferation have been reported previously. METHODS AND RESULTS: All patients were females ranging in age from 44 to 70 years. The lesions appeared as solitary or multiple papules or vesicles localized to the field of radiation. Microscopically, they were composed of vascular spaces that exhibited atypical features without qualifying for a diagnosis of angiosarcoma. CONCLUSIONS: Our cases provide additional evidence supporting the benign nature of this atypical vascular proliferation, not recurring, never developing metastases and being cured readily by local excision. Clinical, histopathological and ultrastructural findings suggest a lymphatic origin. Whether these lesions represent a neoplastic or a reactive condition secondary to radiotherapy is unclear. The name 'benign lymphangiomatous papules of the skin following radiotherapy' is proposed.

Angiofibroblastoma of the skin: a histological, immunohistochemical and ultrastructural report of two cases of an undescribed fibrous tumour.

AIMS: The aim of this report is to present two cases of a distinct mesenchymal tumour of the skin that does not fit into one of the established entities. METHODS AND RESULTS: All cases of fibromyxoid tumours from the files of two dermatopathology centres, together with clinical data and histopathological records, were reviewed. Two cases of a lesion composed of stellate and spindle-shaped cells with the phenotype of fibroblasts embedded in a fibromyxoid to dense fibrous stroma were identified. Because of the large number of capillary-sized blood vessels and their peculiar distribution within the stroma, the name angiofibroblastoma of the skin is proposed for this peculiar neoplasm. In both cases, the tumour appeared as an indolent and slowly growing nodule on the extremities of adults. Immunohistochemical and, in one case, ultrastructural studies were performed. CONCLUSIONS: The lack of recurrences during a follow-up period of 9 and 3 years, respectively, after complete excision together with the bland histopathological appearance supports the benign character of the tumour.

Classification of cutaneous malignant melanoma: a reassessment of histopathologic criteria for the distinction of different types.

BACKGROUND: Human cutaneous malignant melanoma currently is classified into four principle types: nodular, superficial spreading, lentigo maligna, and acral lentiginous. The criteria for the histopathologic diagnosis of these types are not applied consistently. Nevertheless, the classification has become the foundation of many clinical, histopathologic, epidemiologic, and molecular studies. The results of those studies can have validity only if the classification itself is valid. For this reason, the authors reassessed histopathologic criteria advocated for the distinction of the different types of melanoma and searched for other repeatable constellations of findings that may serve to define distinct subsets of the neoplasm. METHODS: Nine hundred fifteen melanomas were examined with regard to 72 parameters that are considered to be important for histopathologic diagnosis. The results were analyzed statistically with special attention to findings that have been reported to be characteristic of the four principle types of melanoma. RESULTS: The histopathologic criteria advocated for the distinction of different types of melanoma were found not to correlate with one another. A logistic regression analysis did not detect any other repeatable constellation of morphologic findings that may reflect a distinct biologic subgroup. CONCLUSIONS: The validity of the current classification of cutaneous malignant melanoma into four principle types could not be substantiated. Malignant melanoma may present with many different forms, but these forms appear to be part of a continuous spectrum rather than examples of distinct biologic entities.

Histopathologic diagnosis of superficial soft tissue tumors, related lesions, and simulators: an algorithmic approach based on colors.

An algorithmic approach based on colors for histopathologic diagnosis of soft tissue tumors and their simulators is proposed. At scanning magnification, in specimens stained with H&E, mesenchymal tumors can be classified according to their color. The color of a tumor is basically determined by density, morphology and distribution of neoplastic cells, and by density and quantity of the stroma. The basic colors that can be observed by neoplasms stained with H&E are white, pink, red, and blue. Colors may be used as a first step to choose the algorithm for specific diagnosis of a given mesenchymal neoplasm. Furthermore, colors may be helpful in understanding the histogenesis of a tumor and this is especially important in soft tissue pathology, because criteria for benignancy and malignancy vary according to the nature of the neoplasm.

Pigmented atypical fibroxanthoma.

AIM: The purpose of this report is to call attention to a pigmented variant of atypical fibroxanthoma that resembles malignant melanoma, both clinically and histopathologically. METHODS AND RESULTS: Thirty-eight cases of atypical fibroxanthoma were examined for the presence of pigmented areas. Four such cases were found. Neoplastic cells showed erythrophagocytosis and accumulation of haemosiderin pigment in the cytoplasm. In three cases, immunohistochemical studies using a battery of antibodies were performed. Neoplastic cells were strongly positive for vimentin and weakly positive for CD68, whereas they were negative for melanocytic markers, including S100 protein, HMB45, and the monoclonal antibody NK1-C3 to melanoma-associated antigen. CONCLUSIONS: Pigmented atypical fibroxanthoma represents a poorly recognized variant of the neoplasm that may be easily misinterpreted as malignant melanoma. To the best of our knowledge, this is the first report of erythrophagocytosis in atypical fibroxanthoma.

Sclerosing dermatofibrosarcoma protuberans.

Dermatofibrosarcoma protuberans is a low-grade sarcoma of the skin with well characterized clinical and histopathological features. The lesion frequently appears as a plaque on the trunk or on the extremities of middle-aged adults. Microscopically, the tumor is composed of monomorphous spindle cells arranged in storiform pattern and embedded in a sparse to moderately dense fibrous stroma. We report on two unusual cases of dermatofibrosarcoma protuberans in which neoplastic cells were diffusely replaced by sclerotic tissue in more than 50% of the entire tumor. In both cases, no external trauma or radiotherapy were recorded. Since tumor regression has been defined as a loss of tumor mass in the absence of any treatment (or trauma) we believe that sclerosis in DFSP may represent a manifestation of regression and not, as previously suggested, a new variant of the neoplasm.

[Syringocystadenoma papilliferum and trichoblastoma within a sebaceous nevus]. / Syringocystadenoma papilliferum und Trichoblastom innerhalb eines Naevus sebaceus.

Since birth, a 43 year-old man displayed a nevus sebaceus on the right temple. The histopathology revealed two distinct adnexal neoplasms associated with this lesion: a syringocystadenoma papilliferum and a trichoblastoma. We describe the combination of these entities in this report.

Verrucous angiosarcoma of the skin: a distinct variant of cutaneous angiosarcoma.

AIMS: Cutaneous angiosarcoma is a malignant vascular neoplasm with well established clinical and histopathological features. Epidermal changes in cutaneous angiosarcoma other than atrophy and necrosis have not been described. In this study, we report three cases of a peculiar variant of angiosarcoma with striking verrucous changes of the overlying epidermis. METHODS AND RESULTS: On light microscopy, verrucous changes characterized by marked pseudocarcinomatous epithelial hyperplasia with hypergranulosis, compact orthokeratosis, and papillomatosis were present overlying an angiosarcoma in the dermis. Clinically the lesions presented as violaceous to brown scaly verrucous nodules or plaques. All lesions developed on an extremity. CONCLUSIONS: Verrucous epidermal changes seem to be a manifestation of pseudocarcinomatous hyperplasia, presumably caused by lymphoedema and the superficial setting of the tumour in the papillary dermis. It is important to be aware of this presentation of angiosarcoma because verrucous epidermal changes may be seen in a wide variety of skin diseases. Furthermore, a biopsy that includes the dermis is necessary to ensure that the angiosarcoma underlying the hyperplastic epidermis is correctly identified. The descriptive appellation verrucous angiosarcoma of the skin is proposed to designate a newly recognized variant of angiosarcoma.