Solitary fibrous tumor of the skin.

Solitary fibrous tumor (SFT) is an uncommon mesenchymal tumor that typically arises in the pleural cavity. Comprised of spindled cells characteristically arranged in diverse architectural patterns, SFT histologically simulates a variety of benign and malignant mesenchymal tumors. The diagnosis of SFT has been refined by the availability of newer immunohistochemical markers such as CD-34 and factor XIIIa, facilitating the identification of SFTs arising in multiple extrapleural sites, including the skin. We describe three cases of primary cutaneous SFT, review the literature, and discuss the histologic and immunohistochemical differential of other cutaneous tumors that SFT can mimic.     

A Case of Solitary Fibrous Tumor of Subungual Region

Solitary fibrous tumor (SFT) is a relatively uncommon mesenchymal neoplasm that usually arises in the pleura, but also has been reported in numerous extrapleural locations, including cutaneous site. The skin lesion presents as a circumscribed nodule or tumor, mainly on the head and neck. A 41-year-old male presented with 6 months history of nail lesion without symptom on the left third finger. The lesion is slightly yellowish discoloration with subungual erythematous nodule and distal onycholysis. Biopsy specimen from the nail lesion showed the spindle cells form patternless pattern with hypercellular and hypocellular area. And small blood vessels and dilated vascular spaces were present. The result of special stain for specimen showed that positive for CD34, Bcl-2, and CD99 but negative for S-100, FactorXIIIa, and smooth muscle action. Recognition of this uncommon location of SFT is important because of possible confusion with other subungual tumors, including glomus tumor, fibroma and other fibrohistiocytic tumors like dermatofibrosarcoma protuberans, superficial acral fibromyxoma and cellular digital fibroma. Here in, we report a case of SFT of subungual region. We think this case is interesting because of uncommon location and may be helpful to more understand the character of this disease.     

Cutaneous and subcutaneous fibrohistiocytic tumors of intermediate malignancy: an update

The fibrohistiocytic tumors of intermediate malignancy are uncommon mesenchymal tumors, which typically occur in the skin and subcutis and which may pose significant problems for the dermatopathologist. This article reviews the clinical, histopathologic, and genetic features of dermatofibrosarcoma protuberans, giant cell fibroblastoma, angiomatoid (malignant) fibrous histiocytoma, plexiform fibrous histiocytoma, and soft tissue giant cell tumor (of low malignant potential). The differential diagnosis of these tumors with a variety of benign and fully malignant cutaneous soft tissue neoplasms is discussed.     

Cutaneous solitary fibrous tumor: a report of 2 cases and review of the literature

Solitary fibrous tumor is an uncommon mesenchymal neoplasm that can arise in both pleural and extrapleural locations. Composed of spindled cells intimately admixed with collagen bundles arranged in a "patternless pattern," this heterogeneous tumor can mimic a variety of benign and malignant mesenchymal neoplasms. We present the histological and immunohistochemical findings of two primary cutaneous solitary fibrous tumors, discuss the differential diagnosis, and review the literature. Although solitary fibrous tumors in cutaneous and subcutaneous regions are extremely rare, it should be considered in the differential diagnosis of primary spindle cell neoplasms of the skin.     

Proliferating Hybrid Follicular Tumor

Solitary fibrous tumor (SFT) is an uncommon mesenchymal neoplasm that typically arises in the pleural cavity but may also be seen at extra‐pleural sites including liver, lung, thymus, orbit, soft tissue, and rarely the skin. The diagnosis of cutaneous SFT is challenging due to its histologic variability and lack of distinctive immunophenotype. We report a case of SFT with unusual histologic and immunophenotypic findings. A 23‐year‐old man presented with a two‐year history of a painful, enlarging scalp mass. Histologic examination revealed a variably cellular neoplasm composed of tumor cells with uniform oval nuclei embedded in a collagenous matrix. In areas there was a prominent hemangiopericytoma‐like vasculature. The tumor was strongly immunoreactive for CD34 and had some immunoreactivity for S100. The diagnosis of SFT was rendered based upon the histologic features and strong immunoreactivity for CD34. Immunoreactivity for S100 is rarely seen in SFT. The tumor had a mitotic rate of 8/50 hpf. Mitotic rates greater than 5/50 hpf have been associated with aggressive behavior in SFTs of soft tissue. The significance of aggressive histologic attributes with clinical outcome is yet to be determined in cutaneous SFT. Cutaneous SFTs should be considered in the differential diagnosis of superficial spindle cell tumors.     

Primary cutaneous solitary fibrous tumor with entrapped eccrine components

First described in the pleura, solitary fibrous tumor (SFT) was subsequently reported in a variety of organ systems. Compared to other anatomic sites, primary cutaneous and superficial SFTs are relatively rare. Although several histopathologic variants of cutaneous and superficial SFT have been described, a primary cutaneous SFT harboring glandular components has not hitherto been documented in the literature. The current case report describes a spindle cell neoplasm of the right finger in a female patient with characteristic morphologic and immunohistochemical features of a SFT. Unexpectedly, various glandular and ductal components were identified in the SFT. A few hyperplastic lobules of sweat glands demonstrating similar morphology as the intratumoral glandular components and composed of secretory coils displaying mucinous metaplasia and ducts were detected in the attached subcutaneous tissue, suggestive of an inductive or obstructive effect of the SFT on the eccrine units. The intratumoral glands and ducts were judged to represent entrapped benign eccrine components from the attached subcutaneous tissue. Since this variant of SFT with entrapped eccrine components could mimic many biphasic epithelial and stromal tumors, pathologists should be aware of this unusual variant of SFT to avoid potential erroneous diagnosis, particularly mistaken confusion with a biphasic synovial sarcoma.     

Solitary fibrous tumors are immunophenotypically distinct from mesothelioma(s)

INTRODUCTION: Solitary fibrous tumor is a soft tissue tissue tumor of unknown histogenesis. Based upon histologic similarities and CD-34 expression, it has been suggested that these neoplasms bear some relationship to mesothelioma, and may represent its extra-pleural equivalent. METHODS: In order to further investigate this possible relationship, we examined a series of five dermal and five extra-cutaneous solitary fibrous tumors with antibodies directed against the mesothelial markers calretinin and HBME-1. RESULTS: All the lesions failed to stain with the antibodies tested. This suggests that despite some similar histologic and immunophenotypic features, these lesions are not immunophenotypically identical. Mesotheliomas are CD-34(+), calretinin(+), HBME-1(+), while solitary fibrous tumors are CD-34(+), calretinin(-), HBME-1(-). CONCLUSIONS: The histogenesis of solitary fibrous tumor remains elusive. It is unlikely that tumor location or tumor de-differentiation accounts for the dichotomous staining properties, as these neoplasms show a similarly benign histologic appearance regardless of location.     

Subcutaneous solitary fibrous tumor

We describe a unique case of subcutaneous solitary fibrous tumor (SFT) in a 56-year-old female patient. The patient had been aware of a painless soft mass in her back for ten years. The lesion was surgically excised. Histological examination revealed that the well-defined mass was composed of a proliferation of spindle-shaped fibroblastic cells and polygonal cells embedded in a fibrous matrix corresponding to the so-called "patternless pattern". A prominent pericytomatous pattern (hemangiopericytoma-like structures), focal myxoid changes, and thick hyalinized collagen fibers were also observed. Immunohistochemical stainings for CD34 and bcl-2 were positive in the tumor cells. These features are compatible with SFT. We suggest that SFT should be included in the differential diagnosis of subcutaneous spindle cell tumors.     

Osteochondrolipoma: a subcutaneous lipoma with chondroid and bone differentiation of the chest wall

Lipomas are the most common subtype of benign soft tissue neoplasms and can occur anywhere in the body. Differentiation into a diversity of mesenchymal elements, such as blood vessels, fibrous tissue or muscle, is a frequent event. However, the presence of bone or cartilage in these tumors is extraordinarily rare with very few cases reported in the head and neck area. We report a case of an 'osteochondrolipoma' of the chest wall, in a young individual, providing a rationale in support of this as a possible and distinctive histologic subtype of lipomas, as well as discussion in the differential diagnosis of this lesion.     

Solitary fibrous tumors of the skin: a clinicopathologic study of 10 cases and review of the literature

Solitary fibrous tumor (SFT) is a relatively uncommon neoplasm that most commonly arises in the pleura. However, SFT is now known to affect various other anatomic sites as well, including rare examples in the skin, where the histologic features of this lesion may create diagnostic confusion with a variety of other spindle-cell tumors. In order to further the characterization of cutaneous SFT, all available cases of that entity were retrieved from the authors' institutional files. Immunohistochemical analysis for CD-34, CD-99, vimentin, bcl-2, factor XIIIa, S100 protein, smooth muscle actin, pankeratin, epithelial membrane antigen (EMA) and desmin was performed on those neoplasms and the corresponding clinical information was obtained whenever possible. There were eight men and two women in the study group, with a median age of 43 years. Sites of involvement included the trunk (two cases), cheek (two), scalp (one), forehead (one), lip (one), temple (one), heel (one) and toe (one). All patients were treated with local excision; only one lesion recurred locally, but it required multiple re-excisions. All of the neoplasms were composed of bland spindle cells with a variably fibrous but focally hyalinized collagenous stroma. A variety of case-specific growth patterns were observed. Mitoses were generally rare, ranging from 0 to 3 per 10 x400 microscopic fields. Immunostains showed reactivity for vimentin in all SFTs, CD-34 in 8 of 10 cases, CD-99 and bcl-2 in 4 of 10 (each) and smooth-muscle actin in 3 of 10 cases. None of the lesions was labeled for factor XIIIa, keratin, EMA, desmin or S100 protein. SFT of the skin appears to be a 'borderline' neoplasm that only uncommonly recurs. Immunoreactivity for CD-34, - especially together with bcl-2 or CD-99, or both - is helpful in identifying this tumor.     

Case for diagnosis

Lipomas are common benign mesenchymal tumors composed of mature fat cells that may or may not be surrounded by a thin, fibrous capsule. The link with trauma has already been described. Lipomas involving the fingers are extremely rare but must be considered in the differential diagnosis of benign soft tissue masses in this particular location.     

Solitary fibrous tumor of the vagina

We report of a solitary fibrous tumor (SFT) of the vagina and discuss the differential diagnosis. This is the first SFT documented, to our knowledge. SFTs should be included in the differential diagnosis of fibroblastic, myofibroblastic, and neural lesions of the skin, subcutaneous tissue, and mucosa and can be distinguished from other spindle cell neoplasms at those sites.     

Pedunculated hemangiopericytoma-like tumor: peculiar fibroepithelial polyp or fibrous histiocytoma variant

Abstract:  Pathologists are continually challenged with the difficult task of discriminating between innocuous disease processes and potentially malignant entities. Apropos of this concern, we present a series of three cutaneous polypoid lesions that simulated fibroepithelial polyp, yet upon close scrutiny yielded histologic features of solitary fibrous tumor (SFT) or hemangiopericytoma. These pedunculated lesions showed a storiform pattern of spindled cells with interspersed gaping vascular channels reminiscent of SFT or hemangiopericytoma. Interestingly, the immunohistochemical staining profile of these lesions was negative for CD34 and positive for bcl-2 and factor XIIIa. These findings were discordant with SFT and suggest a relationship with fibrous histiocytoma. We propose that this entity represents a hitherto described variant of fibrous histiocytoma known as pedunculated hemangiopericytoma-like fibrous histiocytoma.     

Fibrohistiocytic skin tumors

The fibrohistiocytic tumors of the skin are a heterogeneous group of dermal/subcutaneous mesenchymal neoplasms which show fibroblastic, myofibroblastic and histiocytic (macrophage‐like) differentiation, often one beside the other in the same tumor. “Fibrohistiocytic” means in this context the morphologic similarity of the cells with fibroblasts and histiocytes. The WHO classification of 2005 includes the following entities as fibrohistiocytic tumors of the skin: Benign: 1. Fibrous histiocytoma (FH)/(synonymous: Dermatofibroma. Variants of FH: 1a. cellular fibrous histiocytoma, 1b. atypical (pseudosarcomatous) fibrous histiocytoma, 1c. aneurysmatic fibrous histiocytoma, 1d. epithelioid fibrous histiocytoma; 2. dermatomyofibroma; 3. (juvenile) xanthogranuloma. Intermediate: 4. plexiform fibrohistiocytic tumor; 5. dermatofibrosarcoma protuberans; 6. atypical Fibroxanthoma. Malignant: 7. malignant fibrous histiocytoma. All these entities are reviewed in this paper with particular attention devoted to differential diagnostic considerations.     

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.     

Differential expression of connective tissue growth factor gene in cutaneous fibrohistiocytic and vascular tumors

Connective tissue growth factor (CTGF) is a member of a family of immediate early gene products that may play an important role during tissue regeneration, wound repair and skin fibrosis. In this study, CTGF gene expression in mesenchymal tumors was investigated by in situ hybridization and CD34 antigen expression was studied by means of immunohistochemical staining. CTGF mRNA was expressed in fibroblasts of all nine dermatofibromas examined, but five of seven dermatofibrosarcoma protuberans (DFSP) or two cases of malignant fibrous histiocytoma were negative for its expression. In contrast, CD34 antigen was expressed only in DFSP. In vascular tumors, CTGF mRNA was expressed in pyogenic granuloma but not in angiosarcoma. In addition, the endothelial cells in angiolipoma and angioleiomyoma, but not in venous lake, expressed CTGF mRNA. These vascular lesions were all positive for CD34 expression. Tumors of other origins were negative for CTGF mRNA. Our findings indicated that benign fibroblasts and/or vascular endothelial cells have the capability to express CTGF mRNA when activated, but these cells lose this ability when they achieve malignant potency. Thus, examination of CTGF gene expression may be useful for differentiating between benign and malignant mesenchymal tumors, or to determine the origin of the tumors in connective tissue.     

A case of benign mesenchymoma containing cartilageous tissue components with enchondral ossification

A 50-year-old man with benign mesenchymoma containing cartilageous tissue components with enchondral ossification was reported. The tumor was located in the soft tissue of the right leg. Microscopically, it was composed of lipomatous, myxolipomatous or angiolipomatous, hemangiomatous, myxomatous, and fibrous connective tissue in addition to the ossifying cartilageous tissue components. We have found 21 cases of benign mesenchymoma in the Japanese literature and determined that our case with cartilageous components showing enchondral ossification was unique among a variety of well-differentiated mesenchymal components.     

Malignancies of the eyelid: a review of primary and metastatic cancers

The eyelid can be the site of various malignant tumors, including epithelial, mesenchymal, lymphoproliferative, and endocrine neoplasms, all of which can present in unusual ways or mimic benign processes, often requiring biopsy for a definitive diagnosis. This review article presents a broad overview of some of the malignancies that have been reported to occur in eyelids, addressing clinical presentation and natural history, histologic and immunostaining characteristics, and genetic associations where relevant. The unique combination of functional importance, to protect and lubricate the eye, and cosmetic importance make management of eyelid lesions difficult. We describe a few of the diagnostic and treatment options that can be considered.     

Adenomatoid tumor of the skin: Differential diagnosis of an umbilical erythematous plaque

Adenomatoid tumors are benign tumors of mesothelial origin that are usually encountered in the genital tract. Although they have been observed in other organs, the skin appears to be a very rare location, with only one case reported in the literature to our knowledge. We report a second case of an adenomatoid tumor, arising in the umbilicus of a 44‐year‐old woman. The patient presented with an 8‐month‐old erythematous and firm plaque under the umbilicus. A skin biopsy showed numerous microcystic spaces dissecting a fibrous stroma and lined by flattened to cuboidal cells with focal intraluminal papillary formation. This little‐known diagnosis constitutes a diagnostic pitfall for dermatopathologists and dermatologists, and could be misdiagnosed as other benign or malignant entities. Through this case report, a practical approach and diagnostic keys have been devised to avoid misdiagnosis and overtreatment.     

Fibrous hamartoma of infancy. Eight additional cases and a review of the literature

Fibrous hamartoma of infancy is a benign but persistent soft-tissue tumor that appears during the first two years of life. Although the lesion is not distinctive clinically, histopathologic examination of affected tissue reveals the three characteristic elements: fibrous, adipose, and myxoid mesenchymal tissue. Sixty-seven patients with fibrous hamartoma of infancy have been described previously, few in the dermatologic literature. In this report, we describe eight additional patients and present a compilation of the clinical statistics of all 75 cases.