[The ultrastructure of fibrous and histiocytic skin tumors (dermatofibroma, dermatofibrosarcoma protuberans, fibroxanthoma, and histiocytoma) (author's transl)]

Dermatofibrosarcoma protuberans with EMa+ cells. Report of a case suggesting perineurial cell differentiation

A case of dermatofibrosarcoma protuberans (DFSP) with epithelial membrane antigen (EMA)-positive cells is described. The tumor was excised from the left groin of a 28-year-old woman. It showed characteristic histologic features of DFSP with typical diffuse immunohistochemical positivity for CD34. Moreover, scattered neoplastic cells expressed EMA, suggesting perineural cell differentiation. Ultrastructural study found perineurial cell features, such as thin long bipolar cytoplasmic processes, pinocytotic vesicles, fragments of external lamina and/or external lamina-like material, attachment plaques, and desmosome-like junctions. This observation, together with previous immunohistochemical findings of EMA-positive cells in a subset of DFSPs, strongly suggests perineurial cell differentiation in these tumors. DFSP should be included in the differential diagnosis of EMA-positive spindle cell lesions of superficial soft tissue and skin.

Granular cell dermatofibroma

We herein describe the histopathologic findings of an otherwise stereotypical dermatofibroma replete with granular cells. The histopathologic diagnosis of dermatofibroma was underlined by immunohistochemical findings and ultrastructural examination. Cellular granularity is the result of cytoplasmic accumulation of lysosomal structures and can be observed not only in conventional granular cell tumor but in a variety of benign and malignant cutaneous neoplasms. Granular cell dermatofibroma represents a hitherto undescribed variant of dermatofibroma that can be added to the broad histopathologic spectrum of this benign fibrohistiocytic proliferation.

Dermatofibrosarcoma protuberans

Dermatofibrosarcoma protuberans is a tumor of intermediate malignancy characterized by its aggressive local growth and marked propensity to recur after surgical excision. This article reviews the incidence, clinical presentation, histologic features, immunocytochemical studies, histogenesis, prognosis, management, and follow-up recommendations for this unusual neoplasm.

Dermatofibrosarcoma protuberans is a unique fibrohistiocytic tumour expressing CD34

Dermatofibrosarcoma protuberans (DFSP) is a slow growing, locally invasive tumour whose differentiation from other fibrohistiocytic tumours sometimes poses serious diagnostic problems. We investigated CD34 expression immunohistologically in various fibrohistiocytic tumours including dermatofibroma, DFSP, malignant fibrous histiocytoma (MFH), infantile myofibromatosis, fibrosarcoma, hypertrophic scar and keloid. Among these, DFSP was unique in that tumour cells themselves expressed CD34, whereas in other tumours. CD34 expression was observed only on vascular endothelial cells amongst the tumour cells. Until now, there have been no reports of useful immunohistological markers for DFSP. CD34 expression by the tumour cells can be an extremely useful marker in establishing a definitive diagnosis of DFSP.

Giant cell fibroblastoma. A juvenile form of dermatofibrosarcoma protuberans

A clinicopathologic analysis of 28 cases of giant cell fibroblastoma (GCF), a rare mesenchymal tumor occurring predominantly in the first decade of life, is presented. This disease presented as a painless, slowly enlarging, subcutaneous mass. The tumor recurred locally in 47% of the patients; however, metastasis was not detected. On microscopic examination, GCF showed an unique combination of spindle cell patterns, pleomorphic and multinucleated giant cells, myxoid areas, and distinctive sinusoid-like spaces. This unrecognized histomorphologic picture led to a misdiagnosis of sarcoma in 40% of the cases. The histogenesis of this lesion remains uncertain; however, based on both clinical and morphologic similarities, it is proposed that GCF is a juvenile form of dermatofibrosarcoma protuberans (DFSP).

Multinucleate cell angiohistiocytoma: a clinicopathological, immunohistochemical and ultrastructural study

The term 'multinucleate cell angiohistiocytoma' was first introduced by Smith and Wilson Jones in 1985. We report the clinicopathological, immunohistological and ultrastructural findings observed in two patients. Multinucleate cell angiohistiocytoma occurs mainly in middle-aged women and is usually located at acral sites, particularly the distal extremities. Grouped, brown-red, slightly elevated, asymptomatic papules slowly develop over several months until further growth ceases. There is no evidence of systemic disease. Histologically, the dermis shows numerous well developed capillaries with prominent endothelia, large bizarre basophilic and often multinucleate cells with a sparse lymphohistiocytic infiltrate. The immunohistological and ultrastructural findings suggest a fibroblastic differentiation of the large multinucleate cells.

The proliferation behavior of bone tumors investigated with the monoclonal antibody Ki-67

Specimens of several tumor entities at various grades of malignancy were selected from the Bone Tumor Registry of Westphalia for an immunohistological study of their proliferation behavior. Using the monoclonal antibody Ki-67 directed against a nuclear antigen present in all active phases of the cell cycle (G1, S, G2, and M), we were able to demonstrate the growth fractions in tissues with an atypical rate of proliferation, implying an increased risk of malignant transformation. In the 97 cases examined we found a good correlation of the biological proliferation behavior with the expression of the nuclear antigen Ki-67. Moreover, our immunohistological results are comparable with the data from the same tumor entities obtained by other methods such as flow cytometry and autoradiography. Thus the monoclonal antibody Ki-67 provides an excellent marker for labeling the growth fraction in a human tissue. Its practical impact lies in the differential diagnostic analysis of the proliferation rate in a given tumor and its possible grading, and in pre- or posttherapeutic monitoring of patients and the establishment of a prognosis.

Pigmented dermatofibrosarcoma protuberans (Bednar tumour): melanocytic colonization or neuroectodermal differentiation? A clinicopathological and immunohistochemical study

Approximately 5% of cases of dermatofibrosarcoma protuberans contain dendritic melanocytes; such lesions are often known as Bednar tumours. These neoplasms have received little attention in the literature but seem to show no great clinicopathological differences from conventional dermatofibrosarcoma protuberans except for the presence of melanocytes. The existence of such tumours, combined with ultrastructural evidence, has led some leading authors to regard them all as being of neuroectodermal origin. Seven examples of the pigmented variant are presented herein, of which six have been studied immunohistochemically and one has been examined ultrastructurally. Except for the presence of melanocytes in each tumour, no evidence of neuroectodermal (in particular perineural fibroblastic) differentiation has been demonstrated. The histogenesis of dermatofibrosarcoma protuberans and its pigmented variant is discussed. The possibility that the pigmentation may simply reflect secondary melanocyte colonization from the epidermis should be considered.

Atypical fibroxanthoma of the skin: a clinicopathological and immunohistochemical study and a discussion of its histogenesis

The morphological and immunohistochemical characteristics of 37 atypical fibroxanthomas of the skin were examined. Twenty-four tumours were nodular ulcerative lesions on the head and face of patients with a median age of 75 years, whereas 13 tumours occurred on the trunk and limbs of patients with a median age of 48 years. Both pleomorphic polygonal and giant cells as well as the spindle cell component of the tumours stained for the histiocytic markers alpha 1-antichymotrypsin, alpha 1-antitrypsin, lysozyme and, less frequently, for ferritin. Leu M1 antigen and peanut agglutinin receptors were not demonstrable in tumour cells. This antigenic profile was contrasted with the findings in six cases of dermatofibroma which were largely not reactive with the antisera used. The immunohistochemical findings in atypical fibroxanthomas suggest that they represent a homogeneous group of tumours which are related to tissue histiocytes. These results are discussed in the context of the published findings in other so-called fibrohistiocytic tumours including dermatofibrosarcoma protuberans and malignant fibrous histiocytoma. The diagnoses in three cases coded as atypical fibroxanthomas were revised on the basis of their showing a different immunohistochemical profile.

The fibroblastic nature of dermatofibrosarcoma protuberans: morphological investigations in vivo and in vitro

Six cases of dermatofibrosarcoma protuberans were studied ultrastructurally. Biopsy material from all six cases as well as cell cultures derived from four cases were examined. In all cases, the tumor cells in vivo and in vitro were related to fibroblasts. The two cases with histiocytoid features and a small spiral pattern exhibited numerous lipid vacuoles but no histiocytic cell markers. In these two cases, cultured cells contained a higher number of intracytoplasmic vacuoles than the control fibroblasts. Two other cases exhibited some basement-membrane-like material surrounding tumor cells. All of the investigated cell strains obtained from the tumors showed synthesis of collagenous proteins similar to that found in fibroblasts. However, the level of total collagen was reduced, and type-III collagen was absent. The morphological variations in these cases of dermatofibrosarcoma protuberans appeared to be related to the histological pattern and may reflect the heterogeneity of normal fibroblasts.

Dermatofibrosarcoma protuberans: a clinicopathological and immunohistochemical study with a review of the literature

Forty-one cases of dermatofibrosarcoma protuberans are presented. The clinical features and histopathological appearances are described. Immunohistochemical staining of thirteen cases with antisera to lysozyme, alpha 1-antichymotrypsin and S-100 protein has provided no evidence to support either a histiocytic or neuroectodermal origin for these tumours. In reviewing the literature, the histogenetic origin, differential diagnosis and malignant potential of dermatofibrosarcoma protuberans are discussed.

Dermatofibrosarcoma non-protuberans: description and report of five cases of a morpheaform variant of dermatofibrosarcoma

Five cases of dermatofibrosarcoma are reported. All showed features typical of dermatofibrosarcoma protuberans except that in four cases, and a portion of the fifth case, no protusion of the tumor was noted clinically despite the rather advanced stage of growth of the tumor. These lesions resembled morphea or a morpheaform basal cell carcinoma clinically but could be recognized as "dermatofibrosarcoma non-protuberans" by physicians who had observed a previous case.

Dermatofibrosarcoma protuberans of the vulva

A woman aged 52 years had a tumor of the mons pubis. The morphologic picture, featuring a whirling of spindle cells with long slender, interdigitating cell processes and so-called labyrinth nuclei, conformed to a dermatofibrosarcoma protuberans. Wide local excision is sufficient therapy, but more experience with this rare sarcoma of the vulva is necessary.

Benign fibrous histiocytoma of bone. Light- and electron-microscopic observations

Case report of a patient with an unusual, rapidly growing bone tumor in the third and fourth cervical vertebrae. Histological and electron-microscopic investigations reveal a tumor composed of histiocytic cells, xanthomatous cells, giant cells of Touton type, and fibroblastic cells. No cellular features of malignancy are observed. From its cytologic appearance the tumor has to be classified as a benign fibrous histiocytoma. Regarding its ultrastructural features, the tumor may not be distinguished from non-ossifying fibroma of bone, but its clinical pattern shows obvious differences of localization and growth potential. the term "benign fibrous histiocytoma of bone" is proposed for these tumors which must be differentiated from non-ossifying fibroma.

Incidence and histological structure of the storiform pattern in benign and malignant fibrous histiocytomas

A starlike arrangement of cells and fibers, the "storiform pattern", was found to be a typical, but not obligatory, histological feature of benign and malignant fibrous histiocytomas. In 155 benign fibrous histiocytomas storiform structures were missing in 29 cases, chiefly of the fibroblastic type comparable with classical "dermatofibroma". 12 of 70 malignant fibrous histiocytomas did not reveal storiform structures, especially the cellular pleomorphic variant, i.e. the classical pleomorphic sarcoma. Storiform structures were either small and highly cellular with few fibers (collagen type III), or larger, less cellular, but with abundant fibers (collagen type I). There was no sharp demarcation between these two extremes, but many transitional structures or patterns were seen. The histiocytic nature of the cells was demonstrated in both variants of storiform structures by immunhistochemical methods on paraffin embedded material. Alpha 1-antichymotrypsin was especially valuable in this respect.

Malignant fibrous histiocytoma of the renal capsule

We report about an extremely rare case of malignant fibrous histiocytoma (MFH) of the renal capsule. The tumor is composed of fibroblast-like cells arranged in a storiform pattern and histiocyte-like cells with multinucleated giant cells, both showing no iron reaction. Characteristic of the histiocytic quality of the tumor are numerous PAS-positive intracytoplasmic droplets which can be identified as erythrophagosomes only under the electron microscope. Emphasis is put on the preoperative differential diagnosis of the tumor from renal cell carcinoma as well as on its histogenesis and prognosis.

The fibroblastic nature of dermatofibrosarcoma protuberans. A tissue culture and ultrastructural study

Dermatofibrosarcoma protuberans has been considered to be of fibrohistiocytic or fibroblastic origin. The purpose of this paper is to identify the original cell strain from which this neoplasm derives, using tissue culture and electron microscopic methods. Thirteen cases of DFSP characterised by clinical, topographical, histological and behavioral criteria were explanted. The emigrating cells were bipolar with two opposed processed and showed a radial arrangement in respect to the explants. After the second week the distal processes tended to curve back towards the cell body forming flame-like structures. This cell morphology and cellular orientation persisted during the whole life of the culture. Electron microscopy was performed in three cases; the newly grown cells maintained an electron microscopic picture similar to that found in the original tumors. This pattern of behaviour is characteristic of fibroblastic tumors and has been found in explants of normal fibroblasts, of fibromatosis and of fibrosarcomas used as controls. On this basis, we believe that DFSP is a fibrosarcoma of the skin of low grade malignancy.

Malignant fibrous histiocytoma of bone. Light microscopic and electron microscopic examination of four cases

Malignant fibrous histiocytoma (MFH) of bone is a well-defined tumor by light microscopy but no agreement has been achieved concerning its histogenesis. We present the light and electron microscopic findings of four cases of MFH of bone. In case 1 multiple bone tumors were observed and in case 4 the tumor developed after irradiation. It was our aim to document the cytological variability and to arrange the findings in a histogenetic concept of primary intraosseous MFH. We observed some undifferentiated cells but mainly histiocyte- and fibroblast-like cells including intermediate forms, and several types of giant cells. We should emphasize the fact that there were also some large cells with a light microscopic resemblance to rhabdomyoblasts and with electron microscopic characteristics of myoblastic differentiation. From the ultrastructural point of view, therefore, MFHs seem to derive from a primitive mesenchymal stem cell rather than from the ordinary histiocyte. It is suggested that osteosarcoma and MFH of bone may have a common progenitor cell but it is important to make a clear clinico-pathological distinction between the tumors because of differing biological behavior.

[Histochemical and electron microscopical studies of histiocytoma (author's transl)]

In histiocytomas the alkaline phosphatase technique reveals a surprising number of capillaries. The capillaries branch out from the center to the periphery of the histiocytoma and even the capillaries beneath the epidermis proliferate. The cellular elements outside the capillaries, however, are fibroblasts, histiocytes and mast cells, as is revealed by various histochemical and electron microscopical examinations. Histiocytomas of short duration differ from older histiocytomas in that the former contain fibroblasts similar to those found in healing wounds (C-fibroblasts).

Myofibroblasts in connective tissue capsules around implanted dental materials

For testing the biocompatibility of dental materials in an experimental animal model the capsular tissues around the implanted dental materials were examined light and electron microscopically. The exudative inflammation and fibrosis at different times after implantation were thought to be the indicators of the degree of the compatibility. Starting from the knowledge of the occurrence of myofibroblasts in reparative granulation tissue we looked for such cells in the capsular tissues. Myofibroblasts were especially found at three weeks after onset of the experiments. Structural peculiarities of this fibroblast modulation are emphasized. Myofibroblasts are considered as an essential link between the early exudative reaction and the late fiber formation in tissue reactions after mechanical injury.

Desmoid tumors. An ultrastructural study of eight cases

A prominent ultrastructural finding in eight desmoid tumors was myofibroblastic mesenchymal cells with abundant intercellular collagen. In addition, seven of the tumors had intracytoplasmic collagen fibers. These findings are discussed in relation to other tumors and to nontumorous conditions.

Dermatofibrosarcoma protuberans. An ultrastructural study of five cases

An ultrastructural study of five cases of dermatofibrosarcoma protuberans revealed that the basic cell was a spindle shaped fibroblast with a peculiar deeply lobulated nucleus. An origin from perineural and endoneural cells could not be established since basal lamina material was sparsely present in only one case and other differential features were missing. In one case histiocytic cells were found, but also in this case the basic cell was the fibroblast; so evidence of relationship with fibrous histiocytoma was not found.

Fibrous histiocytoma: an analysis of the storiform pattern

A storiform pattern is an important structural feature of fibrous histiocytoma (FH). In this analysis reconstructions of histological patterns were carried out from drawings. Highly FH with only a suggestion of storiform pattern and small star-formations were seen, there were other lesions with more pronounced fiber formation which showed more distinct and larger storiform stars. These structures can frequently be followed for only 3 sections of 5 micron thickness. In contrast to leiomyomas or meningioma, no regular or consistent orientation of these structures with respect to vessels is evident. Storiform structures apparently develop at the periphery of adjacent proliferating cells groups. They show a typical and diagnostically significant histological pattern, which was found to some degree in all FH examined.

Fibrous histiocytoma: a histological and statistical analysis of 155 cases

Various salient histological features were rated from + to +++ in a semiquantitative evaluation of a series of 155 cases of fibrous histiocytoma. Relations between individual histological features, as well as between histological findings, localisation and size of lesions, and age or sex of the patient were tested statistically. Most impressive was an inverse proportional relationship between cellular and fibrillar densities: highly cellular fibrous histiocytomas chiefly showed little fiber formation. Accordingly, cases with marked fiber formation were distinguished by low cellularity. Based on this statistically significant relation, 3 subtypes could be classified on a scale of increasing fiber formation and decreasing cellular density. The majority of cases showed medium cellularity and fibrillar density, with distinct storiform (spokewheel or "whirlygig") pattern which is compatible with typical storiform histocytoma, including clincally progressive, recurrant FH and/or "dermatofibrosarcoma protuberans". The typical patient was more frequently female than male, 40 years of age with a 0.5 to 1.0 cm size tumor node in the lower extremities located in the corium, often with beginning infiltration of the subcutaneous fat tissue.

The ultrastructure of mycobacterium marinum granuloma in man

3 biopsies of 3-5 week-old nodular lesions in 2 patients with so-called swimming-pool (aquarium-) granuloma have been examined by electron microscopy. The cytohistological spectrum simultaneously comprises acute exudative as well as chronic proliferative phenomena. Epithelioid cells and collagen producing fibroblasts are already conspicious in 3 week-old granuloma. According to the cytological composition the Mycobacterium marinum granuloma represents a high-turnover granuloma with immunogenic origin. It is comparable to mycobacterial diseases in the presence of well developed cell mediated immunity (Lupus vulgaris, tuberculoid leprosy). Degrading mycobacteria have been rarely detected in phagocytes and are compared with viable bacilli in macrophages of experimentally infected mice. Curved and annular parallel membranes ("worm-like structures") in the cytoplasm of transformed macrophages and in fibroblasts presumably originate from the membranes of endoplasmic reticulum. Cord-like structures with transverse bands (periodicity 170-180 A) in the lumen of RER of some fibroblasts are interpreted as intracellularly aggregated collagen precursors.

Malignant fibrous histiocytoma. An electron microscopic study

Sixteen cases of malignant fibrous histiocytoma are presented. Electron microscopy of 15 cases demonstrated fibroblast-like and mononuclear and multinucleated histiocyte-like cells. A small capillary was at the center of all storiform areas examined. Ultrastructural examination can be diagnostically useful within the context of a narrow differential diagnosis by conventional microscopy and the ability, by electron microscopy, to eliminate other mesenchymal cell types. In 13 cases, follow-up information was available from 18 months to 9 years following histological diagnosis. Five patients are alive and 8 patients have died, including two non-tumor related deaths. In 3 cases follow-up was less than 4 months. The biologic behavior of the tumor in this series was generally not related to histopathological parameters. The issue of histogenesis is largely unresolvable. Ultrastructural studies of various types of fibrous histiocytomas, suggesting cells of origin other than histiocytes, give credence to the concept that the histiocyte may represent a morphologic state of a given mesenchymal cell rather than a particular cell type.