Subungual pleomorphic fibroma

BACKGROUND: Pleomorphic fibroma is a benign fibroblastic tumor characterized by pleomorphic, hyperchromatic cells or giant multinucleated cells embedded in a collagenous stroma. These cytologic features may lead to an incorrect diagnosis of malignancy. Most cases reported in the literature are located on trunk or extremities; the presentation as a subungual mass is rare. METHODS: We report an unusual case of a subungual pleomorphic fibroma in 66-year-old woman. Clinical information was obtained. Histologic examination and immunohistochemical studies were performed. RESULTS: A 66-year-old woman presented with a longstanding (40 years), subungual mass that deformed the nail of the left middle finger. Microscopic examination revealed a paucicellular tumor composed of hyperchromatic spindled, pleomorphic, floret-like giant cells embedded in haphazardly arranged collagen bundles in the dermis. No mitotic figures were seen. The tumor cells were vimentin-positive but did not stain with antibodies to S-100, cytokeratin, smooth muscle actin, factor XIIIa or CD34 negative. The diagnosis of a pleomorphic fibroma was made. Follow-up shows no evidence of tumor, 36 months after excision. CONCLUSION: Pleomorphic fibroma of the subungual region is an unusual cutaneous tumor with histologic features that may cause confusion with true sarcomas. This is only the second case reported of a subungual pleomorphic fibroma. Pleomorphic fibroma should be considered in the differential diagnosis of pleomorphic subungual tumors.     

Pleomorphic fibroma of the skin with MDM2 immunoreactivity: A potential diagnostic pitfall

Pleomorphic fibroma is a rare benign cutaneous neoplasm characterized by spindle‐shaped cells and multinucleated giant cells scattered throughout collagenous stroma. These morphologic features can lead to diagnostic confusion, including atypical lipomatous tumor as one consideration. In contrast to atypical lipomatous tumor, previous studies have found pleomorphic fibroma to be negative for MDM2 immunohistochemical staining and MDM2 gene amplification. Here, we present a case of pleomorphic fibroma of skin with nuclear MDM2 immunoreactivity in the absence of MDM2 gene amplification, underscoring the superiority of fluorescence in situ hybridization as a diagnostic test in this differential diagnosis. The RB1 locus is also explored for differential diagnosis with pleomorphic/spindle cell lipoma and related entities.     

Pleomorphic sclerotic fibroma

We report the clinical and histologic features of 2 cutaneous tumors demonstrating many of the usual features of sclerotic fibroma, an entity that is well described in the literature. Our cases differed from the usual form of sclerotic fibroma in that they demonstrated marked focal cellular pleomorphism without increased mitotic activity. We suggest the term pleomorphic sclerotic fibroma for these lesions.     

Pleomorphic fibroma of the skin,a form of sclerotic fibroma: an immunohistochemical study

We report a new case of pleomorphic fibroma of the skin arising on the face. The lesion was polypoid and fibrous, located on the dermis, and formed by coarse collagen bundles with sparse cells. It was also characterized by the presence of cellular atypia and pleomorphism without mitosis. Immunohistochemistry showed staining for vimentin and actin and negativity for S-100, CD34, CD68, α-1-antichymotrypsin and α-1-antitrypsin antigens, supporting a myofibroblastic origin. A few isolated cells also showed granular cytoplasmic detection of factor XIIIa. Although the disorder has been previously considered to be a tumour of preferential localization on the trunk or extremities, this does not always hold true as four of the 14 reported cases arose on the head. Pleomorphic fibroma is a benign condition and is we believe a variant of sclerotic fibroma.     

Dermal pleomorphic liposarcoma resembling pleomorphic fibroma: report of a case and review of the literature

Pleomorphic liposarcoma (PLPS) is a rare, high‐grade sarcoma defined by the presence of pleomorphic lipoblasts. Constituting 5% of all liposarcomas, PLPS usually arises in deep soft tissues of the extremities, with rare occurrences in the dermis and subcutis. We describe a unique case of an 85‐year‐old Caucasian gentleman with a 1 year history of a pedunculated, pink, non‐tender papule on the dorsum of his left arm, measuring 1.0 cm in maximum dimension. Biopsy revealed a dermal collection of atypical epithelioid and spindle cells superimposed on a sclerotic background, resembling a pleomorphic fibroma on low power. On high power, a central focus of discrete adipocytic differentiation with pleomorphic lipoblasts was present. Tumor cells were positive for S‐100 and negative for desmin, actin, CD68, keratin, MART‐1 and CD34. Clinicopathologic findings were consistent with PLPS and the diagnosis was made. PLPS is rarely localized to the dermis and one with low power features resembling a pleomorphic fibroma has not been previously described in the literature.     

Sclerotic fibroma: A fossil no longer

We report on a patient with a sclerotic Fibroma that recurred 30 months after initial removal. The histologic features were characteristic, and immunoperoxidase stains using primary antibodies directed against cell proliferation markers were positive in a significant proportion of the neoplastic nuclei. A review of the literature identified one other sclerotic fibroma that persisted. These clinical and light microscopic features support the interpretation that sclerotic fibroma is a proliferating neoplasm with an unusual histologic pattern, rather than the end-stage of a process that was formerly more cellular. We advocate use of sclerotic fibroma as the preferred diagnostic term.     

Solitary sclerotic fibroma of the skin: morphological characterization of the 'plywood-like pattern'

Sclerotic fibroma is an uncommon skin tumor. Rapini and Golitz reported 11 cases of solitary sclerotic fibromas in patients without Cowden's disease in 1989. We report a case of sclerotic fibroma that presented as an asymptomatic nodule in a 34-year-old Japanese man. Histopathological examination revealed typical features of sclerotic fibroma of the skin. Ultrastructural examination showed that spindle cells with myoid features had proliferated around the vasculature. They had segregated from the perivascular area by leaving the surrounding basal lamina, resulting in their phenotypical change to produce collagen accumulating in a concentrically lamellar fashion. We suggest a possible role of abnormal blood vessels and surrounding specific cells in the development of sclerotic fibroma.     

Dermatofibroma with sclerotic areas resembling a sclerotic fibroma of the skin

BACKGROUND: Dermatofibromas are common benign tumors that occur as single or multiple nodules on the extremities in adults. Sclerotic fibroma of the skin (SFS) is a benign tumor characterized histopathologically by a well-demarcated, non-encapsulated dermal nodule composed of hypocellular, sclerotic collagen bundles with prominent clefts. The pathogenesis of these two conditions is still in dispute. METHODS: We present a case of dermatofibroma with sclerotic areas resembling a sclerotic fibroma of the skin and a review of the literature. RESULTS: The tumor showed a well-demarcated dermal, fibrocollagenous tumor with three different histopathological features. One-fourth of the lesion was consistent with dermatofibroma. Another area adjacent to dermatofibroma revealed hyalinized eosinophilic collagen bundles arranged in the characteristic interwoven pattern with prominent clefts, as is described in sclerotic fibroma of the skin. One-half of the lesion between the dermatofibroma and sclerotic fibroma showed transitional changes from dermatofibroma to sclerotic fibroma. CONCLUSION: According to these findings, the possibility that sclerotic fibroma is an ancient or degenerated stage of dermatofibroma cannot be completely ruled out, but some authors still consider that dermatofibroma and sclerotic fibroma of the skin are completely different neoplasms.     

Myxoid pleomorphic fibroma of the skin

Pleomorphic fibroma of the skin was described by Kamino et al 1 in 1989. It is a benign fibroblastic proliferation with cytologic atypia. This article describes a case of a myxoid variant of pleomorphic fibroma of the skin.     

Solitary sclerotic fibroma of the skin: degenerated sclerotic change of inflammatory conditions, especially folliculitis

Two cases showing changes of sclerotic fibroma developed in association with an inflammatory process, especially folliculitis. The lesion in the first case showed a well-circumscribed, nonencapsulated nodule in the dermis, which consisted of a perifollicular fibrotic area and a peripheral sclerotic area. In addition to the usual findings of sclerotic fibroma, spindle cells were heavily infiltrated in a storiform and fascicular pattern around the degenerated hair follicle, suggestive of dermatofibroma. The lesion in the second case showed the typical findings of sclerotic fibroma in association with folliculitis and hair follicle remnants. Our observations suggest that solitary sclerotic fibroma of the skin may be a degenerated or sclerotic end stage of other fibrous conditions, such as dermatofibroma, and that it may be induced by inflammation, especially folliculitis.     

Giant cell collagenoma: case report and review of the literature

BACKGROUND: Giant cell collagenoma (GCC) is a recently described cutaneous fibrous neoplasm that usually affects young to middle-aged adults. Despite its similar histological appearance with circumscribed storiform collagenoma, no association of GCC with Cowden's syndrome has been described so far. To the best of our knowledge only five cases of this rare fibrous tumor have been reported so far. METHODS: We report a case of a 79-year-old male patient presenting with a slow growing flesh-colored dome-shaped lesion in his left forearm, with a clinical diagnosis of fibroma. No stigma of Cowden's syndrome was depicted. RESULTS: The histological analysis showed a symmetrical and well-circumscribed flat-dome-shaped lesion covered by an atrophic overlying epidermis. The neoplasm was composed of hyalinized collagen bundles disposed in a whorled storiform pattern. Admixed with the collagen matrix, there were two distinct cell populations, one composed by spindle-shaped mononuclear cells, and the other composed by bizarre multinucleated giant cells. Immunohistochemical analysis showed positivity for vimentin and actin HHF35 in the mononucleated. The multinucleated cells only immunoexpressed vimentin. CONCLUSION: GCC is an unusual cutaneous fibrous tumor that should be differentiated from circumscribed storiform collagenoma, pleomorphic fibroma, regressive forms of dermatofibroma, and solitary myofibroma based on its histological features.     

Cutaneous metastasis of pleomorphic liposarcoma to the scalp: an elusive diagnosis

Liposarcomas are one of the most common sarcomas arising in the extremities of the elderly. Various subtypes of liposarcomas include well‐differentiated liposarcomas, dedifferentiated liposarcomas, myxoid liposarcomas and pleomorphic liposarcomas. Pleomorphic liposarcomas are the rarest subtype and have the highest malignant potential compared with the other subtypes of liposarcomas. Metastases to internal organs are common but cutaneous metastasis is very rare with only few cases in the literature. We present a patient with a known diagnosis of stage IV metastatic liposarcoma who presented to our clinic with a rapidly growing nodule on the scalp. A biopsy showed a high‐grade poorly differentiated spindled cell neoplasm sparing the epidermis with scattered lipoblasts. Immunostaining for S100, SOX10, and MNF‐116 were negative. To further characterize the neoplasm, immunostaining with MDM‐2 was performed and was also found to be negative. The histologic appearance, immunohistochemical staining, and clinical history support a diagnosis of metastatic pleomorphic liposarcoma to the scalp. The diagnosis of pleomorphic liposarcoma is challenging. It is often difficult to differentiate from myxofibrosarcoma or other high‐grade pleomorphic sarcomas based on histology alone. However, the presence of bizarre lipoblasts and negative MDM‐2 staining can be helpful clues to differentiate this neoplasm from histologic mimics.     

Solitary sclerotic fibroma of skin: a possible link with pleomorphic fibroma with immunophenotypic expression for O13 (CD99) and CD34

BACKGROUND: Solitary sclerotic fibroma (SF) presents as a well circumscribed dermal nodule, composed of sparse spindle cells with alternating wavy collagen fibers arranged in a storiform pattern. The histogenesis and nature of this histologically distinct lesion are uncertain. Whether this peculiar tumor represents a true hamartoma or a degenerating end of various fibrous lesions such as pleomorphic fibroma (PF), dermatofibroma, or angiofibroma is still controversial. High proliferating index of spindle cells in SF argues against the possibility of being a degenerating end product of another lesion. METHODS: We studied morphological features and immunoprofile of eight SFs, in comparison with four PFs, one collagenized dermatofibroma, two angiofibromas, and two periungual fibromas. Immunostains for CD34, CD31, O13 (CD99), Factor XIIIa, S-100, CD68 (KP-1), and MIB-1 were carried out using a labeled streptavidin-biotin method with DAKO-automated immunostainer. Paraffin blocks of two SFs were reprocessed for electron microscopic studies. Clinical data of all patients with SF were also reviewed. RESULTS: Spindle cells and pleomorphic cells in SF and PF showed diffuse immunoreactivity for CD34 and O13 but were negative for CD31, S-100, and CD68. Spindle cells in one dermatofibroma and one angiofibroma were positive for Factor XIIIa. Proliferating index (MIB-1) was very low in all cases of SF, contradicting some previous reports. CONCLUSIONS: SF is a fibrotic lesion with cells positive for CD34 and O13. It shares a common immunoprofile with PF but is distinct from dermatofibroma and other common spindle cell lesions of skin. O13 expression in SF has not been previously described.     

Sclerotic (fibroma-like) lipoma: a distinctive lipoma variant with a predilection for the distal extremities

This report details the clinicopathologic and immunohistochemical findings identified in 21 cases of a fibrosclerotic variant of lipoma from acral sites that is frequently misdiagnosed as a fibromatous (nonlipogenic) process. The study includes 12 males and 9 females; aged 7 to 72 (mean and median, 39). The patients presented with solitary, mostly asymptomatic, masses that ranged from 0.6 to 2.2 (median, 1.2; mean, 1.3) cm and involved fingers (n=17), hands or wrists (n=3), and toes (n=1). Microscopically, the lesions were well-circumscribed nodules that showed very low to moderately low cellularity and consisted of cytologically bland spindled and stellate-shaped cells and a minor component of randomly dispersed adipocytes embedded in a collagenous to myxocollagenous stroma. Eight tumors were "fibroma-like" owing to their paucity of spindled cells, dense fibrosclerotic stroma, and inconspicuous vasculature. One tumor showed features of spindle cell/pleomorphic lipoma, whereas another demonstrated a vague onion skin-like arrangement of collagen reminiscent of sclerotic (storiform) fibroma. In all cases, the mitotic activity was negligible. Nonlipogenic tumor cells were immunoreactive for CD99 (6 of 6 cases), CD34 (6 of 8), S-100 protein (4 of 7), and smooth muscle actin (2 of 6). Follow-up data on 8 patients (range, 1 to 20 years; median, 9.5 years) revealed no recurrence in 6, but indicated the possibility of persistent tumor in the remaining 2 individuals after simple excision. Despite histological overlap in 1 case with the sclerotic fibroma, no patient displayed definitive clinical features of Cowden syndrome. Our study indicates that fibrosclerotic lipomas demonstrate a broader histological scope than what was initially described.     

Pleomorphic angiomatoid fibrous histiocytoma: a case confirmed by fluorescence in situ hybridization analysis for EWSR1 rearrangement

Angiomatoid fibrous histiocytoma (AFH) is a neoplasm of uncertain histogenesis with intermediate malignant potential. It occurs in superficial soft tissues in any age group and at any body site, although the typical example occurs on extremities in children/young adults. The neoplasm is usually composed of a bland histiocytoid proliferation of cells with eosinophilic cytoplasm forming a syncytium, often surrounded by a dense fibrous pseudocapsule and lymphoid infiltrate, with abundant intralesional hemorrhage forming blood-filled spaces. AFH may show striking pleomorphism and mitotic activity, and such cases can lead to confusion with other atypical mesenchymal lesions, including pleomorphic sarcomas. Recent findings have shown that a majority of cases of AFH have translocations involving the EWSR1 or FUS genes. We present a diagnostically challenging case of AFH with pleomorphic features and minimal lymphoid and angiomatoid changes involving the superficial subcutis and deep dermis on the scalp of an 8-year-old boy. "Areas with typical AFH morphology were identified and the diagnosis confirmed with identification of an EWSR1…" rearrangement detected by fluorescence in situ hybridization. Pleomorphic AFH should be included in the differential diagnosis of atypical mesenchymal tumors of skin and superficial subcutis and molecular testing may prove helpful in this regard.     

Pleomorphic fibroma and dermal atypical lipomatous tumor: are they related?

Pleomorphic fibromas represent dome‐shaped or polypoid cutaneous lesions characterized by a paucicellular and densely fibrotic background punctuated by scattered atypical to pleomorphic spindle and multinucleated giant cells. Some of these tumors will have incorporated adipose tissue, although these adipocytic areas lack distinct cytologic atypia and may represent entrapped normal periadnexal or subcutaneous adipose tissue. Nonetheless, owing to the similarity of some of the morphologic features of pleomorphic fibroma with cutaneous atypical lipomatous tumor, diagnostic confusion can ensue. The potential diagnostic challenges are further highlighted by a recent report of a lesion with histopathologic features of both. In response, we studied the presence of 12q15/ MDM2 amplification by fluorescence in situ hybridization and MDM2 expression by immunohistochemistry in a series of 15 pleomorphic fibromas to investigate whether these two entities share a common pathogenic origin. One case of cutaneous atypical lipomatous tumor was used as positive control for 12q15 amplification. All 15 cases were negative for MDM2 by immunohistochemistry with no demonstrable 12q15/MDM2 amplification by fluorescence in situ hybridization. Therefore, these two entities are best regarded as pathogenetically distinct. MDM2 immunohistochemistry or fluorescence in situ hybridization studies can be used to differentiate between the two if needed.     

Keloidal atypical fibroxanthoma: a case series

Background:  Keloidal atypical fibroxanthoma (AFX) is a rare variant of AFX with thick bands of hyalinized collagen. The identification of keloidal collagen associated with fibrohistiocytic cells may erroneously lead to the diagnosis of keloidal dermatofibroma. Although AFX is a pleomorphic cutaneous tumor typically associated with a good prognosis, occasional reports of metastatic AFX highlight the importance of accurate identification.
Methods:  A total of nine cases of an unusual variant of AFX with keloidal tumoral sclerosis were collected and examined. The cases were stained with antibodies directed against S100, cytokeratin, CD68 and CD31.
Results:  Histopathological examination revealed pleomorphic cells trapped within hyalinized keloidal collagen bands. In several cases, the keloidal collagen also formed ring-shaped structures surrounding CD31-positive vascular structures. Pleomorphic cells were negative for S100 protein and keratin, but consistently labeled with antibodies directed against CD68.
Conclusions:  The diagnosis of keloidal AFX requires the exclusion of other malignant and benign lesions with keloidal or sclerotic collagen. Awareness of the rare variant of keloidal AFX may avoid a diagnostic pitfall leading to an erroneous diagnosis, particularly in small biopsies. The finding of sclerotic collagen preferentially deposited around vessels is an interesting and poorly understood phenomenon.     

Sclerotic fibromas of the skin.

We report a case of a 34-year-old Japanese woman with a fibrous tumor on the left palm that fulfilled the criteria of sclerotic fibroma of the skin. Immunohistochemically, the tumor cells were positive for vimentin, but negative for S-100 protein and neuron-specific enolase. Ultrastructurally, the cross-striations of collagen microfibrils were less prominent. Our case supports the concept that sclerotic fibroma of the skin is a distinctive lesion which may represent a hamartoma of the skin.     

Solitary sclerotic fibroma

A 63-year-old Chinese man with a solitary sclerotic fibroma on the abdomen is described. Skin biopsy showed a well-demarcated dermal nodule composed of hypocellular, eosinophilic collagen bundles separated by prominent clefts. Retrospective electron microscopic study revealed wide collagen bundles containing tightly packed collagen fibrils, only 50 nm in diameter. There were no signs of Cowden's disease. To our knowledge, this is the first report of electron microscopic study of sclerotic fibroma. A brief review of the literature is included.