Dermatofibrosarcoma protuberans is a unique fibrohistiocytic tumour expressing CD34

Subcutaneous atypical fibrous histiocytoma

Benign fibrous histiocytoma is one of the most frequent benign neoplasms mainly composed of a mixture of fibroblastic and histiocytic cells, especially found in the skin (dermatofibroma), particularly in the limbs. The diagnosis of cutaneous benign fibrous histiocytoma is generally easy; however, rare variants may be difficult to identify, and the diagnosis only confirmed after exhaustive histopathological examination. Thus, deep subcutaneous dermatofibroma may be difficult to distinguish from dermatofibrosarcoma protuberans and dermatofibroma with monster giant cells from malignant fibrous histiocytoma and atypical fibroxanthoma. We report a case of a 38-year-old woman with a painless swelling on the abdominal wall, which was totally excised and histopathologically diagnosed as subcutaneous atypical fibrous histiocytoma. The lesion was deeply located within the subcutaneous tissue and consisted of interlacing fascicles of predominant histiocyte-like spindle cells intermingled with pleomorphic giant cells with bizarre large nuclei (bilobed and multilobed) and prominent eosinophilic nucleoli. Only 1 mitotic figure was found in the whole lesion. Prominent hyaline collagen bundles surrounded by tumor cells were observed, predominantly at the periphery of the lesion. Immunohistochemical study showed positivity only for vimentin and factor XIIIa, whereas pan-keratins, actin, desmin, CD34, CD10, and S-100 protein were negative. Recognition of dermatofibroma is important, allowing sequential excision and optimal results. Definitive diagnosis, although especially difficult in our case, is established by characteristic histological and immunohistochemical criteria. To the best of our knowledge, we report the first case of subcutaneous fibrous histiocytoma with monster cells.

CD34-reactive tumors of the skin. An updated review of an ever-growing list of lesions

Over the past few years, a growing number of cutaneous tumors expressing CD34 is being reported. The list contains benign and malignant neoplasms as well as reactive and hamartomatous lesions of diverse lineages of differentiation, including fibroblastic, myofibroblastic, fibrohistiocytic, vascular, neural, adipocytic, smooth muscle, hematopoietic, melanocytic and epithelial. The more frequent diagnostic difficulties are found in spindle cell proliferations, mainly in those of the fibrocytic lineage. In part, this is because of the fact that in this area are, aside to well-defined entities, histologically and clinically diverse, recently reported cutaneous CD34-reactive lesions, whose definitions, limits and relationships are not completely established. The CD34 expression plays a key role in the differential diagnosis of some tumors, such as dermatofibrosarcoma protuberans, epithelioid sarcoma or pleomorphic hyalinizing angiectatic tumor of soft parts, with important therapeutic consequences. In others, as in desmoplastic trichilemmoma, it can help to resolve diagnostic problems in concrete cases. Finally, in many of the CD34-positive lesions, the diagnosis with the hematoxylin and eosin stain is straightforward. However, in all of them, the knowledge of the immunohistochemical profile contributes to our understanding of the cutaneous pathology.

Congenital atrophic dermatofibrosarcoma protuberans in a 7-month-old boy treated with Mohs micrographic surgery

Dermatofibrosarcoma protuberans is a rare, malignant, slow-growing, locally invasive tumor of the skin. Although most cases are acquired and diagnosed in adulthood, there have been an increasing number of congenital dermatofibrosarcoma protuberans mimicking benign birthmarks described in the literature. The clinical presentation of this tumor is often one of an indurated exophytic plaque or nodule; however, a rare variant can present as atrophic or sclerotic in nature. We report a case of congenital atrophic dermatofibrosarcoma protuberans of the groin in a 7-month-old boy, successfully treated with Mohs micrographic surgery.

Apolipoprotein D in CD34-positive and CD34-negative cutaneous neoplasms: a useful marker in differentiating superficial acral fibromyxoma from dermatofibrosarcoma protuberans

More recent techniques to characterize the genetic profile of soft-tissue tumors include the use of gene arrays. Using this technique, Apolipoprotein D (Apo D), a 33-kDa glycoprotein component of high-density lipoprotein, has been found to be highly expressed in dermatofibrosarcoma protuberans. To corroborate these results, we sought to ascertain the utility of Apo D by investigating its sensitivity and specificity in a variety of CD34-positive and CD34-negative cutaneous neoplasms including superficial acral fibromyxoma, sclerotic fibromas, and cellular dermatofibromas. Of interest, we found absence of Apo D expression in all four cases of superficial acral fibromyxoma. Of the remaining CD34-positive lesions, Apo D expression was noted in 35/36 (97%) cases of dermatofibrosarcoma protuberans, 3/5 (60%) giant-cell fibroblastomas, 4/4 (100%) sclerotic fibromas, 8/8 (100%) neurofibromas, and 1/1 (100%) solitary fibrous tumor. Of the CD34-negative lesions, Apo D expression was noted in 2/22 (9%) regular dermatofibroma, 23/45 (51%) cellular dermatofibroma, 10/10 (100%) malignant fibrous histiocytoma, 9/10 (90%) atypical fibroxanthoma, 7/8 (86%) cellular neurothekeoma, 9/9 (100%) malignant melanoma, 8/8 (100%) melanocytic nevi (100%), 0/2 superficial angiomyxoma, 0/15 fibromatosis, 0/1 nodular fasciitis, and 1/2 (50%) desmoplastic fibroblastomas. In summary, our findings indicate that Apo D expression is not specific to dermatofibrosarcoma protuberans. Its principal use as an immunohistochemical adjunct lies in its utility in differentiating superficial acral fibromyxoma from dermatofibrosarcoma protuberans. Although strong positive staining of Apo D in a markedly atypical fibrohistiocytic lesion is suggestive of atypical fibroxanthoma and/or malignant fibrous histiocytoma, further studies with the inclusion of other atypical spindled cell neoplasms are required to conclusively prove the same.

Solitary Fibrous Tumor of the Female Genital Tract A Case Report and Review of the Literature

Originally thought to be limited to mesothelial-lined surfaces, solitary fibrous tumor (SFT) has now been reported in numerous extrathoracic sites. The female genital tract is among the rarest reported sites involving SFT, and only a handful of cases have been described. Although features pointing to a more malignant biological behavior have been described, these tumors remain unpredictable in their clinical course. We present a case of primary SFT originating in the vulva of a 45-year-old woman, only the fourth such case and only the ninth case of primary SFT of the female genital tract. The tumor presented as a 60-mm, well-circumscribed, painless lump and comprised bland spindle cells in a collagenized stroma with hypercellular and hypocellular foci. Immunohistochemically, the spindle cells were strongly positive for CD34, Bcl 2, and vimentin, with focal positivity for CD99. Immunohistochemical staining for MNF116, desmin, smooth muscle actin, ER, PR, and S100 was negative. There has been no recurrence after 6 months. We discuss the principal differential diagnoses of spindle cell mesenchymal tumors of the vulva and review the previously published cases of primary SFTs originating in the female genital tract. We also stress the importance of informing clinicians involved in these cases of the potential for an unpredictable clinical outcome.

Stromelysin-3 expression in the differential diagnosis of dermatofibroma and dermatofibrosarcoma protuberans: comparison with factor XIIIa and CD34

BACKGROUND

The distinction between dermatofibroma (DF) and dermatofibrosarcoma protuberans (DFSP) is a well-known challenge for dermatopathologists. Immunohistochemical stains have been used to augment routine histological examination to aid in differentiating DF from DFSP. Stromelysin-3 (ST3) is a member of the matrix metalloproteinase (MMP) family, MMP-11, which is expressed in the skin during wound healing and in the stroma of basal cell carcinoma. Recent studies demonstrated that DFs expressed ST3, whereas DFSPs were only rarely ST3 positive.

OBJECTIVES

To assess the expression of ST3 in DF and DFSP and to ascertain whether ST3 is superior to factor XIIIa or CD34 in differentiating DF from DFSP, by comparison with factor XIIIa and CD34 expression.

METHODS

Immunohistochemical staining was performed on 23 cases of DF and 17 cases of DFSP, using antibodies to ST3, factor XIIIa and CD34.

RESULTS

ST3 was expressed in all cases of DF (23 of 23) but only one case showed weakly positive staining in DFSP (one of 17). The mean +/- SD ST3 immunohistochemistry (IHC) score in DF was 4.52 +/- 0.67. The sensitivity of ST3 was 100% and the specificity was 94%. Factor XIIIa was expressed in all cases of DF (23 of 23) and in five of the 17 DFSPs. The mean +/- SD factor XIIIa IHC score in the DFs was 4.43 +/- 0.73. The sensitivity of factor XIIIa was 100% and the specificity was 71%. CD34 was expressed in four of the 23 DFs and 16 of the 17 DFSPs. The mean +/- SD CD34 IHC score in the DFSPs was 4.41 +/- 1.37. The sensitivity of CD34 was 94% and the specificity was 83%.

CONCLUSIONS

Immunohistochemical staining with a commercial anti-ST3 antibody can be successfully carried out in routine dermatopathology. We confirmed that ST3 is a positive marker for DF and that ST3 staining might be more reliable than factor XIIIa staining in differential diagnosis of DF and DFSP. As the present study showed that ST3 was not absolutely negative in all cases of DFSP, the combination with CD34 immunostaining could make the distinction more reliable.

Dermatofibrosarcoma protuberans

Dermatofibrosarcoma protuberans (DFSP) is a soft tissue neoplasm of intermediate malignancy that is initially localized to the skin from where it can invade deep structures (fat, fascia, muscle and bone). It is the most frequent fibrohistiocytic tumor, comprising approximately 1.8 % of all soft tissue sarcomas and 0.1 % of all cancers. It has an estimated incidence of 0.8-5 cases per one million persons per year. Treatment of localized disease consists in complete surgical excision of the lesion by conventional surgery with wide margins (>3 cm) or by micrographic Mohs surgery. Although the cases of metastatic DFSP do not reach 5 % of the total, almost all of them appear after previous local relapses. The prognosis for metastatic cases is very poor with a survival of less than 2 years following detection of metastatic disease. Patients with locally advanced DFSP are not candidates for an initial radical surgical therapy therefore neoadyuvant treatment is required prior to surgery in order to reduce tumor burden. In this regard, chemotherapy and radiotherapy have not been highly efficacious so it is necessary to consider new alternatives. The demonstration of the oncogenic power of the translocation COL1A1-PDGFB in DFSP has allowed the successful introduction of drug therapy with antagonists of the PDGFB receptor for metastatic or locally advanced cases.

Dermatofibrosarcoma protuberans: a population-based cancer registry descriptive study of 66 consecutive cases diagnosed between 1982 and 2002

BACKGROUND

Dermatofibrosarcoma protuberans (DFSP) is a rare malignant tumour of the skin, with an estimated incidence of 0.8 to five cases per 1 million people per year.

OBJECTIVE

To study epidemiological, immunohistochemical and clinical features, delay in diagnosis, type of treatment and outcome of DFSP from 1982 to 2002.

METHODS

Using data from the population-based cancer registry, 66 patients with pathologically proved DFSP were included (fibrosarcomatous DFSP were excluded). Each patient lived in one of the four departments of Franche-Comté (overall population of 1 million people) at the time of diagnosis. The main data sources came from public and private pathology laboratories and medical records. The rules of the International Agency for Research on Cancer were applied.

RESULTS

The estimated incidence of DFSP in Franche-Comté was about three new cases per 1 million people per year. Male patients were affected 1.2 times as often as female patients were. The trunk (45%) followed by the proximal extremities (38%) were the most frequent locations. DFSP occurred mainly in young adults between 20 and 39 years of age. Mean age at diagnosis was 43 years, and the mean delay in diagnosis was 10.08 years. Our 66 patients initially underwent a radical local excision. Among them, 27% experienced one or more local recurrences during 9.6 years of follow-up. There was one regional lymph node recurrence without visceral metastases. These recurrences were significantly related to the initial peripheral resection margins. We observed a local recurrence rate of 47% for margins less than 3 cm, vs. only 7% for margins ranging from 3 to 5 cm [P=0.004; OR=0.229 (95%, CI=0.103-0.510)]. The mean time to a first local recurrence was 2.65 years. Nevertheless, there was no death due to the DFSP course at the end of the follow-up, and the final outcome was favourable.

CONCLUSION

Our study emphasizes the importance of wide local excision with margins of at least 3 cm in order to prevent local recurrence. However, the recent development of inhibitors of signal transduction by the PDGFB pathway should soon modify the surgical strategy, which is often too mutilating.

Análisis del gen de fusión COL1A1-PDGFB en un caso de dermatofibrosarcoma protuberans con componente de fibrosarcoma

Dermatofibrosarcoma protuberans (DFSP) is an infrequent tumor of intermediate malignancy, with little tendency to develop metastases but with a high rate of local recurrence. Cytogenetically, DFSP is characterized by a reciprocal translocation, t(17;22)(q22;q13), which is a conditioning factor in the fusion of the collagen type I alpha I gene (COL1A1) in chromosome 17q with the platelet-derived growth factor beta chain gene (PDGFB) in chromosome 22q. The fusion of these genes is variable, involving one of the 51 exons of the COL1A1 gene and exon 2 of the PDGFB gene. We present the case of a 37-year-old woman with a tumor on the arm whose histology showed a neoplastic infiltration of the subcutaneous cellular tissue made up of fusiform cells with an elongated nucleus in a storiform pattern and other more pleomorphic cells in a herringbone pattern, compatible with DFSP with a fibrosarcoma component. The molecular biology study with RT-PCR analysis of paraffin-embedded material and later sequencing showed a new fusion of exon 19 of the COL1A1 gene and exon 2 of PDGFB, supporting a diagnosis of DFSP. A study of the COL1A1-PDGFB fusion products is useful in cases where histology and immunohistochemistry are insufficient for the differential diagnosis of DFSP versus other sarcomas. It also justifies the use of new avenues of treatment with tyrosine kinase inhibitors.

Clinical variants of the preprotuberant stage of dermatofibrosarcoma protuberans

BACKGROUND

Some cases of dermatofibrosarcoma protuberans (DFSP) do not protrude above the skin.

OBJECTIVES

To assess the prevalence of these DFSPs and further to describe their presentation and course.

METHODS

One hundred and forty-three patients were retrospectively collected. They were asked to complete a standardized questionnaire indicating the history and appearance of the DFSP from the first skin changes identified to the time of diagnosis.

RESULTS

Eighty-one DFSPs were described as protuberant ab initio, and 62 as initially nonprotuberant (npDFSP). The latter remained at this stage for a mean period of 7.6 years. Twenty-nine per cent of npDFSPs were 'morphoea-like', 19% were 'atrophoderma-like' and 42% were 'angioma-like'. Age at diagnosis was similar for both initial presentations. npDFSPs were most often misdiagnosed by physicians.

CONCLUSIONS

Nearly half the patients first identified their early DFSP-related skin changes as patches. Both this frequency and the long duration at this preprotuberant stage should prompt dermatologists to consider the diagnosis of DFSP earlier, in order to make surgical treatment easier.

Unusual variants of malignant melanoma

A potential diagnostic pitfall in the histologic assessment of melanoma is the inability to recognize unusual melanoma variants. Of these, the more treacherous examples include the desmoplastic melanoma, the nevoid melanoma, the so-called 'minimal-deviation melanoma,' melanoma with prominent pigment synthesis or 'animal-type melanoma,' and the malignant blue nevus. Also problematic are the unusual phenotypic profiles seen in vertical growth phase melanomas; these include those tumors whose morphological peculiarities mimic cancers of nonmelanocytic lineage and those melanomas that express aberrant antigenic profiles not commonly associated with a melanocytic histogenesis. Metaplastic change in melanoma, balloon cell melanoma, signet-ring cell melanoma, myxoid melanoma, small cell melanoma and rhabdoid melanoma all have the potential to mimic metastatic and primary neoplasms of different lineage derivations. Abnormal immunohistochemical expression of CD 34, cytokeratins, epithelial membrane antigen, and smooth muscle markers as well as the deficient expression of S100 protein and melanocyte lineage-specific markers such as GP100 protein (ie HMB-45 antibody) and A103 (ie Melan-A) also present confusing diagnostic challenges. In this review, we will discuss in some detail certain of these novel clinicopathologic types of melanoma, as well as the abnormal phenotypic expressions seen in vertical growth phase melanoma.

Sclerosing dermatofibrosarcoma protuberans (DFSP): an unusual variant with focus on the histopathologic differential diagnosis

A 59-year-old man presented with a 10-cm x 8-cm tumoral plaque with a superficial nodule in the interscapular region of the back (Fig. 1). The lesion had been growing for 25 years. As a cystic lesion was suspected, the superficial nodule was biopsied. The histopathologic diagnosis was low-grade sarcoma with sclerosis. Two months after the initial biopsy, the lesion was completely excised, reaching the muscular fascia, with a 2-cm margin and with a free graft. Formalin-fixed paraffin-embedded samples were submitted to histologic and immunohistochemical study (4-microm paraffin sections); frozen tissue was submitted to electron microscopy. For histopathology, sections were stained with hematoxylin and eosin. Immunohistochemistry was performed following standard avidin-biotin immunoperoxidase procedures with primary antibodies for vimentin, CD34, smooth muscle-specific actin, bcl-2, S-100, desmin, myoglobin, factor VIII, p53 (all from DAKO, Copenhagen, Denmark), HHF-35 (Enzo Diagnostics, Farmingdale NY), cytokeratin (AE1/AE3) (Biogenex, San Ramon, CA), and factor XIIIa (Calbiochem Novabiochem Corporation, La Jolla, CA). At low magnification, the histologic study of the initial tumoral nodule revealed a poorly circumscribed mesenchymal proliferation, with fibroblastic-like neoplastic cells arranged in a fascicular and storiform pattern, admixed with extensive areas of sclerosis. At higher magnification, tumoral cells were spindle-shaped with hyperchromatic nuclei and scant cytoplasm. In some areas, sclerosis was so evident that a keloid-like pattern was seen (Fig. 2a). The surgical specimen showed a fibroblastic neoplastic proliferation infiltrating the dermis and hypodermis. In the dermis, cells were arranged in a storiform pattern, whereas in the hypodermis there was a honeycomb or lace-like pattern (Fig. 2b). There were also cellular areas alternating with sclerotic areas, with transitional zones in between, in both the dermis and hypodermis. The immunohistochemical study of the initial tumoral nodule and the surgical specimen showed that tumoral cells expressed vimentin, CD34 (Fig. 3), bcl-2, HHF-35, and smooth muscle actin. Neoplastic cells failed to show positivity with desmin, myoglobin, factor XIIIa, factor VIII, S-100, cytokeratin (AE1/AE3), and p53. An ultrastructural study revealed spindle cells having an irregular contour with a well-developed granular reticulum endoplasmic (REG) system in their cytoplasm, as well as some Golgi complexes and mitochondria. Also visible was the presence of many actin filaments and some myosin condensations (Fig. 4), characteristics of a fibroblastic cell with myofibroblastic differentiation. The final histopathologic diagnosis of the surgical specimen was sclerosing dermatofibrosarcoma protuberans. Two years after surgery, the patient is alive and well.

CD34 expression in primary cutaneous malignant melanoma: apropos of a case and review of the aberrant melanoma phenotype

BACKGROUND

The histological diagnosis of malignant melanoma can be challenging. Immunohistochemical techniques may define a critical role in certain cases, specifically in establishing a primary diagnosis of melanoma. CD34 is a hemopoietic stem cell antigen expressed in bone marrow and endothelial cells, and may also be expressed in vascular and spindle cell tumors; it is generally negative in malignant melanoma.

CASE REPORT

An 83-year-old white female presented with a 3-4 mm area on her right upper back, which had been present for several years. Histologic sections showed a polypoid distortion by sheets and nodules of transformed amelanotic melanocytes lying in intimate apposition to an attenuated epidermis without a concomitant radial growth phase. Tumor cells were extensively S-100 and CD34 positive and showed focal immunoreactivity with melan-A and HMB-45.

DISCUSSIONS

We present a case of malignant melanoma of nodular subtype, which strongly expressed CD34. The spectrum of abnormal phenotypes in malignant melanoma is reviewed, and a possible explanation for the presence of CD34 is discussed. This case demonstrates the potential of malignant melanoma to express CD34, defining an infrequently recognized aberrant phenotype. Whether or not expression of this marker is associated with a more aggressive clinical course remains to be determined.

Cellular digital fibromas: distinctive CD34-positive lesions that may mimic dermatofibrosarcoma protuberans

BACKGROUND

Digital fibromas are common benign acral tumors typically reported as angiofibromas (AFs) or acquired digital fibrokeratomas (ADFs). Cellular variants are not well recognized.

METHODS

We collected 14 acral fibrocytic lesions showing a spindle cell morphology from our files, and evaluated CD34, Factor XIIIa, epithelial membrane antigen (EMA), and S100 protein staining of these lesions. We compared the histologic and immunohistochemical features of these cellular fibromas with five digital AFs, five ADFs, and five digital dermatofibromas.

RESULTS

The 14 cellular digital fibromas showed intersecting fascicles of thin delicate bland spindle cells in the superficial reticular dermis with a fibrotic-to-slight myxoid stroma. The spindle cells in all cases stained strongly for CD34, and only scattered stromal cells stained for Factor XIIIa. Five tested cases were negative for EMA and S100 protein. The digital AFs, fibrokeratomas, and dermatofibromas stained predominately for Factor XIIIa, with no or minimal staining for CD34.

CONCLUSIONS

These findings suggest that a subset of digital fibromas is characterized by a dense cellular proliferation of CD34-positive spindle cells. Awareness of this variant of digital fibroma and its staining pattern is critical in preventing misdiagnosis as dermatofibrosarcoma protuberans, particularly in superficial biopsies.

HSP47 is a useful marker for skin fibroblasts in formalin-fixed, paraffin-embedded tissue specimens

AIM

This study was undertaken to assess whether heat-shock protein (HSP)47 is a useful cell marker for skin fibroblasts in formalin-fixed, paraffin-embedded skin specimens.

BACKGROUND

HSP47, a 47-kDa HSP, is a collagen-specific molecular chaperone localized in the endoplasmic reticulum. HSP47 plays an essential role in collagen biosynthesis in skin fibroblasts.

METHODS

Immunohistochemistry was performed to detect HSP47 in skin fibroblast cultures and skin tissue sections.

RESULTS

Immunostaining for HSP47 clearly detected skin fibroblasts in paraffin tissue sections as well as in fibroblast cultures and frozen tissue sections. HSP47 staining on paraffin sections from diseased skin specimens revealed that skin ulcer, keloid, nodular fascitis, spindle cell lipoma, and dermatofibroma had strong signals for HSP47 compared with the signals obtained from normal skin. Dermatofibrosarcoma protuberans had many HSP47 positive cells, but signals on individual cells were not as strong as those seen from the above benign proliferative disease samples. In neurofibroma, a small number of faintly positive cells were detected. Our double-immunostaining studies also demonstrated that HSP47 staining distinguished skin fibroblasts from CD68-positive histiocytes/macrophages, factor VIII-related antigen-positive endothelial cells, or factor XIIIa-positive dermal dendritic cells. CD34-positive interstitial cells coexpressed HSP47 in spindle cell lipoma.

CONCLUSIONS

These findings indicate that HSP47 staining can detect skin fibroblasts in routine, paraffin-embedded specimens. A panel approach using HSP47 and other cell markers on paraffin sections may help the identification of the cell type involved with mesenchymal proliferative disorders.

Atrophic dermatofibrosarcoma protuberans: an uncommon and misleading variant

A 23-year-old man presented with an atrophic lesion on his left anterior shoulder that had been present for at least 10 years. A previous biopsy had suggested a fibrohistiocytic origin; however, clinically it resembled morphoea or atrophoderma, and the lesion was observed. Fifteen months later, the lesion was noted to have grown slightly. A repeat biopsy showed dermatofibrosarcoma protuberans, with a storiform spindle cell proliferation with positive CD34 staining. The lesion was excised with a 3-cm margin. Awareness of this rare presentation may assist in earlier diagnosis.

Neurofibromatous changes in dermatofibrosarcoma protuberans: a potential pitfall in the diagnosis of a serious cutaneous soft tissue neoplasm

BACKGROUND

Dermatofibrosarcoma protuberans (DFSP) is a low-grade malignant neoplasm that has the potential for aggressive local growth and destruction if not treated appropriately. Although the storiform arrangement of spindle cells in DFSP is relatively characteristic, histologic patterns simulating other benign as well as malignant neoplasms such as dermatofibroma, neurofibroma, malignant fibrous histiocytoma, and atypical fibroxanthoma have been described.

METHODS

We collected and analyzed six cases of probable DFSP in which a specific diagnosis could not be rendered due to the predominant neurofibromatous changes in the histologic sections. In an attempt to reach a definitive diagnosis, the clinical history and physical characteristics of the lesions were taken into account, and all cases were further evaluated using immunostaining for CD34 and S-100 protein.

RESULTS

The average age of the patient was 56 years (range 21-80), and the male to female ratio was 1 : 1. The location of lesions included the scalp, neck, back, and abdomen. All cases displayed two distinct histological patterns: (i) a proliferation of spindle cells with wavy nuclei in a loose mucinous stroma suggesting neural differentiation and (ii) a proliferation of spindle cells which interweaved and filled the reticular dermis extending into the subcutis. The wide variety of clinical impressions and descriptions indicated that the diagnoses were not always straightforward, and clinical information did not always assist in the clinicopathologic correlation. All lesions stained positively for CD34; however, three of six cases also stained positively for S-100. The three cases which were CD34 positive and S-100 negative were likely DFSP, and this was the final diagnosis given. The three cases that were CD34 and S-100 positive did not allow for a straightforward diagnosis.

CONCLUSIONS

DFSP may demonstrate areas with features more characteristic of a benign neural lesion, such as a neurofibroma, which can lead to underdiagnosis and subsequent failure to treat. Clinicians and pathologists should recognize this potential diagnostic pitfall and understand that equivocal clinical information, combined with non-specific immunohistochemical staining patterns, can further complicate the dilemma. In these situations, where DFSP is the likely diagnosis but definitive evidence cannot be obtained, full excision of the lesion should be recommended to avoid mistreatment of a potentially malignant lesion.

Immunostaining melanoma frozen sections: the 1-hour protocol

BACKGROUND

There is significant debate over the use of frozen section processing in Mohs micrographic surgery (MMS) for melanoma. Opponents argue that individual melanocytes are too subtle to view consistently on frozen sections. On the other hand, proponents state that (1) melanocytes are visible on well-prepared frozen sections and (2) MMS using frozen sections for evaluation of melanoma surgical margins achieves comparable recurrence rates when compared with MMS using paraffin-embedded, permanent sections.

OBJECTIVE

To introduce a new immunohistochemical (IHC) staining protocol that consistently produces melanoma frozen section slides in 1 hour that are easily evaluated during MMS.

METHODS

We adapted a polymer-based IHC staining protocol to use with MMS frozen sections for the evaluation of melanoma surgical margins.

RESULTS

When used with antibody directed against MART-1 for frozen section evaluation of melanoma, the section staining is reproducible and specific for melanocytes.

CONCLUSIONS

In contrast to current IHC protocols that are time consuming (2 to 2.5 hours), we present a new frozen section protocol that takes approximately 1 hour to perform. This technique benefits patients, histotechnicians, and surgeons.

Fine-needle aspiration of primary and recurrent dermatofibrosarcoma protuberans

Dermatofibrosarcoma protuberans (DFSP) is a nodular cutaneous mesenchymal tumor of intermediate malignancy. Studies on fine-needle aspiration of DFSP are extremely rare; to our knowledge, only 33 cases have been reported. We have reviewed 14 examples of DFSP in 13 patients. Ten primary tumors were aspirated before surgical biopsy and four recurrent lesions (all from superficial lesions) were also investigated by fine-needle aspiration. All smears were surprisingly homogeneous and composed of isolated spindle cells in all cases (one unsatisfactory smear is excluded). Tissue fragments with a stroriform pattern were seen in 11 cases, fibrillary stromal fragments in 10 cases, naked nuclei in 8 cases, slight to moderate cytonuclear atypia in 5 cases. Mitotic figures, myxoid background, mast cells, and dispersed adipocytes were rare. Giant cells, necrosis, or marked cytonuclear atypia were not seen. DFSP shares morphological characteristics of some low-grade spindle-cell neoplasms. It should be differentiated from other benign low- and intermediate-grade spindle neoplasm such as low-grade fibrosarcoma, fibromyxosarcoma, low-grade malignant peripheral nerve sheath tumor, benign peripheral nerve sheath tumor, nodular fasciitis, and fibrous histiocytoma.

Dermatofibrosarcoma protuberans: A clinicopathological analysis of 10 cases in Asians

Dermatofibrosarcoma protuberans (DFSP) is a locally aggressive cutaneous neoplasm that exhibits a marked tendency for recurrence after local excision. This case series aims to study the clinical, histological and immunohistochemical features of DFSP in Asians. Ten patients with DFSP diagnosed between 1992 and 2001 were reviewed. There were more women than men in a ratio of 4:1. There were six Chinese, two Malays, one Indian and one Eurasian. The mean age was 38 years. The duration of each lesion before excision varied from 6 months to 27 years. Fifty per cent of tumours occurred on the trunk. On histology, all the lesions were dermal-centred spindle cell tumours, extending to the subcutis, and exhibited the characteristic storiform pattern. One tumour also demonstrated fibrosarcomatous changes. Two tumours were of the rare pigmented variant (Bednar tumour). Immunohistochemistry with CD34 was positive in all cases, except the fibrosarcomatous area of one tumour, which was negative for CD34. For comparison, six cases of deep-penetrating dermatofibroma were stained for CD34 and all showed an absence of CD34 expression. Wide excision of the tumour was performed in all cases of DFSP. There was no recurrence after mean follow up of 6 years (range 2.25-9.5 years).

Gene expression patterns and gene copy number changes in dermatofibrosarcoma protuberans

Dermatofibrosarcoma protuberans (DFSP) is an aggressive spindle cell neoplasm. It is associated with the chromosomal translocation, t(17:22), which fuses the COL1A1 and PDGFbeta genes. We determined the characteristic gene expression profile of DFSP and characterized DNA copy number changes in DFSP by array-based comparative genomic hybridization (array CGH). Fresh frozen and formalin-fixed, paraffin-embedded samples of DFSP were analyzed by array CGH (four cases) and DNA microarray analysis of global gene expression (nine cases). The nine DFSPs were readily distinguished from 27 other diverse soft tissue tumors based on their gene expression patterns. Genes characteristically expressed in the DFSPs included PDGF beta and its receptor, PDGFRB, APOD, MEOX1, PLA2R, and PRKCA. Array CGH of DNA extracted either from frozen tumor samples or from paraffin blocks yielded equivalent results. Large areas of chromosomes 17q and 22q, bounded by COL1A1 and PDGF beta, respectively, were amplified in DFSP. Expression of genes in the amplified regions was significantly elevated. Our data shows that: 1) DFSP has a distinctive gene expression profile; 2) array CGH can be applied successfully to frozen or formalin-fixed, paraffin-embedded tumor samples; 3) a characteristic amplification of sequences from chromosomes 17q and 22q, demarcated by the COL1A1 and PDGF beta genes, respectively, was associated with elevated expression of the amplified genes.

Analysis of gene mutations in three cases of dermatofibrosarcoma protuberans (DFSP): ordinary DFSP, DFSP with fibrosarcomatous lesion (DFSP-FS) and lung metastasis of DFSP-FS

BACKGROUND

Fusion of the collagen type I alpha 1 (COL1A1) gene with the platelet-derived growth factor B-chain (PDGFB) gene has been pointed out in dermatofibrosarcoma protuberans (DFSP). Various exons of the COL1A1 gene have been shown to be involved in the fusion with exon 2 of the PDGFB gene.

OBJECTIVE

We studied the breakpoints of the COL1A1 gene using the tumor specimens from three patients with DFSP.

METHODS

Reverse transcriptase-polymerase chain reaction (PCR) was performed using cultured DFSP tumor cells or frozen tissue. Nucleotide sequence analysis was carried out using the PCR products to identify the breakpoints.

RESULTS

Cases 1, 2 and 3 were diagnosed as ordinary DFSP, DFSP with fibrosarcomatous lesion (DFSP-FS) and lung metastasis of DFSP-FS, respectively. The COL1A1-PDGFB fusion transcripts were detected from the tumor specimens. Sequence analysis revealed that the ends of exons 42, 29 and 38 in the COL1A1 gene were fused with the start of exon 2 in the PDGFB gene in case 1, 2 and 3, respectively.

CONCLUSION

This study identified a novel COL1A1 breakpoint, namely, exon 42 of the COL1A1 gene. Detection of the aberrant fusion transcript seems to be useful at differential diagnosis both in primary and metastatic lesions.

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.

A case of childhood dermatofibrosarcoma protuberans without detected cytogenetic abnormality

Dermatofibrosarcoma protuberans (DFSP) is a rare, infiltrative skin tumour of intermediate malignancy, with a limited potential for metastasis but a high rate of recurrence; specific cytogenetic abnormalities are now known. Childhood DFSP has been considered a rarity in the past, but it is now recognized that many cases of childhood DFSP are diagnosed only in adulthood. Despite advances in the understanding of its pathogenesis as well as the development of valuable immunohistochemical and cytogenetic diagnostic techniques, there often remains a significant delay between the initial presentation and diagnosis of DFSP. We report a case of childhood DFSP in which the diagnosis was reached only after a nodular lesion developed in a plaque that was initially present. Causes for delay between initial presentation and diagnosis in childhood DFSP are discussed. Histology and immunostaining in our patient showed the typical features of DFSP, but the G-banded cytogenetic analysis of short-term tissue culture was negative. However, this technique offers only a detection rate between 50% and 80%. Clinicians should be aware of the limitations of newer diagnostic techniques. Increasing recognition amongst paediatricians and paediatric dermatologists that childhood DFSP is not as rare as once believed will probably lead to the use of newer diagnostic methods at an earlier stage, and so reduce the delay between the onset of symptoms and diagnosis.

CD44 and hyaluronate in the differential diagnosis of dermatofibroma and dermatofibrosarcoma protuberans

The histological distinction between dermatofibroma (DF) and dermatofibrosarcoma protuberans (DFSP) may be extremely difficult. CD34 and Factor XIIIa have been used to differentiate DF from DFSP. However, there is an overlap and relative lack of specificity of their expressions. CD44 is a widely distributed integral membrane glycoprotein, which is expressed as a multitude of isoforms generated by alternative splicing of at least 10 different variant exons and post-translational modifications. CD44 is currently thought to be the principal cell surface receptor for hyaluronate (HA), the major component of the extracellular matrix. In this study we aimed to assess the expression of standard CD44 (CD44s) and its isoforms (CD44v3, CD44v4, CD44v5, CD44v6, CD44v7, CD44v7v8, and CD44v10), and HA in DF and DFSP. Immunohistochemical staining was performed on the biopsy specimens of 15 cases of DF and four cases of DFSP, using antibodies that recognize the CD44s, different CD44 isoforms and the hyaluronate binding protein (HABP). Tumor cells displayed a strong CD44s immunoreactivity in all cases of DF whereas a faint HA positivity was observed in the tumor stroma. The DF cells were negative for CD44v3, CD44v4, CD44v6, CD44v7 and CD44v7v8 but showed a strong reactivity for CD44v5 and CD44v10. In contrast, CD44s' expression was significantly reduced or absent in all DFSP lesions and the tumor stroma displayed strong staining for HA. Our results indicate that CD44 and HA can be used as additional diagnostic markers to distinguish DF from DFSP.

Histomorphologic and immunophenotypic analysis of fibrofolliculomas and trichodiscomas in Birt-Hogg-Dube syndrome and sporadic disease

BACKGROUND

Fibrofolliculomas and trichodiscomas are benign dermal neoplasms that likely derive from the mantle of the hair follicle and can occur sporadically or in association with Birt-Hogg-Dube syndrome (BHDS). Little is known about the pathogenesis and immunophenotypic properties of these entities.

METHODS

We investigated the histomorphologic and immnophenotypic properties of 15 fibrofolliculomas and trichodiscomas in two patients with BHDS and eight with sporadic disease.

RESULTS

We found the following: (1) fibrofolliculomas and trichodiscomas occurring in the setting of BHDS show microscopically contiguous histomorphologic features as compared to those occurring sporadically; (2) the immunophenotypic characteristics of syndromic-associated and sporadic types are identical and consist of (3) perifollicular vimentin (+), CD34 (+) and Factor XIII (-) spindle cells.

CONCLUSIONS

Despite subtle histomorphologic differences, trichodiscomas and fibrofolliculomas are immunophenotypically similar, and are thus likely derived from a similar histogenic precursor. Given the previously reported CD34 (+) immunophenotype of the hair mantle, our findings would support an origin of these lesions from the mantle of the hair follicle. The proliferation of CD34 (+) spindle cells seen in conjunction with these lesions should not be confused with other CD34 (+) dermal entities.

Dermatofibrosarcoma protuberans: a clinicopathological study of 20 cases

AIM

To review the dinical and histological data of 20 cases of dermatofibrosarcoma protuberans presenting at two dermatology centres in Lisbon from 1978 to 1998.

PATIENTS AND METHODS

The 20 subjects comprised nine males and 11 females ranging in age from 25 to 79 years, with highest frequency of subjects in the 30-50 year olds. We reviewed the clinical features, histopathological aspects, including morphologic variants and immunohistochemical studies.

RESULTS

Median age at diagnosis was 51 years and the trunk was the most frequent location. The characteristic histologic storiform pattern was seen in all cases. Three subjects presented fibrosarcomatous areas, one with myoid differentiation and another with multinucleated giant cells. Immunohistochemical stains revealed CD34 expression in the 18 specimens tested, FXIIIa was negative, and these two antigens proved important for the differential diagnosis of this neoplasm. Local wide excision was performed in 13 cases and seven patients underwent Moh's micrographic surgery. Follow-up ranged from 2 months to 17 years and three recurrences were recorded, two following classical surgery and one after Moh's surgery; there was no difference in the rate of local recurrence (15%) for the two kinds of treatment in our series.

Molecular targeting of platelet-derived growth factor B by imatinib mesylate in a patient with metastatic dermatofibrosarcoma protuberans

PURPOSE

Dermatofibrosarcoma protuberans is caused by activation of the platelet-derived growth factor B (PDGFB) receptor, a transmembrane tyrosine kinase. We investigated the response of dermatofibrosarcoma protuberans to the tyrosine kinase inhibitor imatinib mesylate.

PATIENTS AND METHODS

A patient with unresectable, metastatic dermatofibrosarcoma protuberans received imatinib mesylate (400 mg bid). Response to therapy was assessed by [18F]fluorodeoxyglucose (FDG) positron emission tomography, magnetic resonance imaging, and histopathologic and immunohistochemical evaluation.

RESULTS

The patient was treated for 4 months with imatinib mesylate. The hypermetabolic uptake of FDG fell to background levels within 2 weeks of treatment, and the tumor volume shrank by over 75% during the 4 months of therapy, allowing for resection of the mass. There was no residual viable tumor in the resected specimen, indicating a complete histologic response to treatment with imatinib mesylate.

CONCLUSION

Imatinib mesylate is highly active in dermatofibrosarcoma protuberans. The dramatic response seen in this patient demonstrates that inhibition of PDGFB receptor tyrosine kinase activity can significantly impact viability of at least one type of solid tumor.

Pleomorphic sclerotic fibroma: a case report and literature review

Pleomorphic sclerotic fibroma is a benign neoplasm exhibiting features of sclerotic fibroma and pleomorphic fibroma. We report another such case. The tumor presented as a firm, 0.5-cm, flesh-colored papule on the forehead of a 72-year-old white man for an unknown duration. Histologic examination revealed a neoplasm in which the superficial portion showed features of a pleomorphic fibroma, the deeper portion showed features of a sclerotic fibroma, and a transitional area was present in between. We propose that pleomorphic fibroma, sclerotic fibroma, and pleomorphic sclerotic fibroma form a spectrum. Pleomorphic sclerotic fibroma may be used as a broad diagnostic term to encompass the spectrum.

Fibrosarcomatous dermatofibrosarcoma protuberans with giant rosettes

A rare case of dermatofibrosarcoma protuberans, which contained low-grade fibrosarcoma with giant rosettes in its recurrence areas is described. The giant rosettes lying in the fibrosarcomatous area produced a pattern similar to that of so-called hyalinizing spindle cell tumor with giant rosettes. The transitions between the tumor components were gradual, and both primary and recurrent lesions showed diffuse immunoreactivity for CD34. The presence of giant rosettes in fibrosarcomatous areas of dermatofibrosarcoma protuberans suggests a possible histogenetic relationship between fibrosarcomatous areas of DFSP and hyalinizing spindle cell tumor with giant rosettes.

Tenascin differentiates dermatofibroma from dermatofibrosarcoma protuberans: comparison with CD34 and factor XIIIa

Differentiation of dermatofibroma (DF) from dermatofibrosarcoma protuberans (DFSP) can be difficult. CD34 and Factor XIIIa have been used to differentiate DF from DFSP. However, there is overlap and lack of specificity of their expression. Tenascin is an extracellular matrix glycoprotein that is involved in embryogenesis, carcinogenesis, and wound healing. The aim of the study was to assess the role of tenascin in DF and DFSP and compare the results with those obtained with CD34 and Factor XIIIa. Immunohistochemical staining was performed on 20 cases each of DFSP and DF, using antibodies to tenascin, CD34 and Factor XIIIa, and the streptavidin biotin technique. Positivity for all 3 antibodies was assessed within the tumors. Tenascin expression was also assessed at the dermal-epidermal junction. Strong tenascin positivity was noted at the dermal-epidermal junction overlying the lesion in 20 of 20 cases of DF (100%) and was negative over the lesion in 20 of 20 cases DFSP (100%). Tenascin was noted within the lesion of 80% of both DF and DFSP (16/20 cases). CD34 was strongly expressed in 16 of 20 (80%) DFSP and 5 of 20 (25%) DF, whereas Factor XIIIa was strongly expressed in 19 of 20 (95%) DF and 3 of 15 (15%) DFSP. Although CD34 was expressed in 80% DFSP and Factor XIIIa in 95% of DF, there was overlap in their expression in the 2 types of tumors. The increased expression of tenascin at the dermal-epidermal junction overlying the lesion in DF but not in DFSP, differentiated these 2 tumors. In contrast, tenascin expression within the lesion did not differentiate DF from DFSP.

Expression of CD34 and bcl-2 in phyllodes tumours, fibroadenomas and spindle cell lesions of the breast

AIMS

Strong expression of CD34 and bcl-2 has been described in solitary fibrous tumours. It has been proposed that these lesions arise from long-lived mesenchymal cells. We tested the hypothesis that spindle cell lesions of the breast arise from similar mesenchymal cells in the mammary stroma.

METHODS AND RESULTS

Sections of phyllodes tumours (26), fibroadenomas (15), myofibroblastomas (two), pseudoangiomatous hyperplasia (five) and myoid hamartoma (one) were stained immunohistochemically for CD34 and bcl-2. Conventional mammary carcinoma is known to be CD34-negative: we therefore stained 11 spindle cell carcinomas and one adenosquamous carcinoma. The mammary stroma, particularly around lobules, stained for CD34. All the lesions (except the carcinomas) showed spindle cell staining for CD34. There was more staining in fibroadenomas than in phyllodes tumours (especially malignant tumours). The staining in phyllodes tumours was typically patchy. In some there was increased or decreased staining adjacent to the epithelium. There were occasional spindle cells positive for bcl-2 in the normal perilobular stroma. bcl-2 was frequently expressed in spindle cells in fibroadenomas, phyllodes tumours and pseudoangiomatous hyperplasia, and rarely in the other lesions.

CONCLUSIONS

The combined expression of CD34 and bcl-2 suggests that fibroadenomas, phyllodes tumours and pseudoangiomatous hyperplasia may arise from long-lived bcl-2-positive mesenchymal cells in the breast in a manner similar to that proposed for solitary fibrous tumours. The absence of CD34 staining in spindle cell carcinomas is of potential diagnostic value in the distinction from malignant phyllodes tumours in difficult cases.

Dermatofibrosarcoma protuberans growing around plantar aponeurosis: excision by Mohs micrographic surgery

BACKGROUND

Dermatofibrosarcoma protuberans (DFSP) is a spindle cell malignancy that has a high local recurrence rate after excision with minimal or no immediate tissue margin assessment. DFSP is exceedingly rare on the palms and soles.

OBJECTIVE

To report a case of a locally aggressive DFSP on the sole excised using Mohs micrographic surgery.

METHODS

Case report and review of the literature.

RESULTS

Mohs micrographic surgery unmasked tumor infiltration that extended around plantar aponeurosis and into underlying plantar muscle fascia.

CONCLUSION

Mohs micrographic surgery should be considered the treatment of choice for DFSP, especially in acral locations. This technique allows the surgeon to trace out deep tumor extensions that may wrap around underlying tendon, a finding that may not be appreciated clinically.

Indeterminate fibrohistiocytic lesions of the skin: is there a spectrum between dermatofibroma and dermatofibrosarcoma protuberans?

Routine histology and immunohistochemistry can usually distinguish dermatofibroma (DF) and dermatofibrosarcoma protuberans (DFSP). DF generally expresses factor XIIIa whereas DFSP generally expresses CD34. The authors report 10 cutaneous fibrohistiocytic lesions combining clinical, histologic, and immunohistochemical features of both DF and DFSP. The lesions had an average size of 1.2 cm (range, 0.4-2.7 cm), and occurred on the trunk (n = 6), extremities (n = 3), and face (n = 1) of four men and six women (average age, 30.6 yrs; age range, 15-50 yrs). Eight lesions exhibited acanthosis and densely cellular fascicles with focal storiform areas. All had keloidal collagen, infiltrated the subcutis in a honeycomb pattern, and had low mitotic counts (0 to 4 mitoses per square millimeter). All were diffusely immunoreactive for factor XIIIa (30%-60% of the neoplastic cells) as well as CD34 (20%-70%). This series raises the possibility of a biologic spectrum between DF and DFSP; however, double-immunolabeling studies showed no notable coexpression of factor XIIIa and CD34 by individual cells, suggesting coexistence of two different cellular populations. After an average follow up of 22.3 months (range, 10-46 mos) in six cases, a single recurrence was documented. The ambiguous histologic features and the potential for local recurrence suggest that performing a complete excision may be prudent in these diagnostically indeterminate lesions.

What are the CD34+ cells in benign peripheral nerve sheath tumors? Double immunostaining study of CD34 and S-100 protein

To determine whether CD34 expression in nerve sheath lesions was found in a unique cell population or in a subset of nerve sheath cells, we performed double immunohistochemical staining using a standard avidinbiotin complex method with 2 separate color developing systems. We studied 40 neurofibromas and 16 neurilemomas. All lesions strongly expressed S-100 in nuclei and cytoplasm. CD34 was detected in cells having ameboid dendritic cytoplasm present in greatest numbers in Antoni B zones of neurilemomas, myxoid zones of neurofibromas, at the periphery of lobules in both tumor types, and condensed in apposition to perineurium. The CD34+ cells also were detected in normal nerves. They were infrequent in Antoni A zones of neurilemomas. No dual S-100 and CD34 expression was seen. This double immunostaining confirms the presence of a CD34-reactive non-Schwannian cell type in these neural neoplasms. As the CD34+, S-100-negative cell population is present also in normal nerves and infrequently seen in the areas of cellular neoplastic Schwann cells, CD34+, S-100-negative cells in peripheral nerve sheath tumors most likely are nonneoplastic and may have a supportive function.

Expression of CD34 in sclerotic ("plywood") fibromas

CD34 antigen is expressed in normal human skin on endothelium, in spindle cells located around adnexal structures, and in a subset of interstitial cells in the reticular dermis. CD34 expression has also been identified in a number of fibrohistiocytic neoplasms, such as dermatofibrosarcoma protuberans and solitary fibrous tumors of soft tissue. CD34 expression has not previously been described in sclerotic, or "plywood" fibromas. Here presented are three lesions from three patients, in which histologic examination revealed a well-circumscribed dermal nodule composed of spindled cells with focal nuclear pseudo-inclusions. There was extensive fibrosis with hypocellular, storiform areas, characteristic of sclerotic fibroma. The spindled cells strongly expressed CD34, but not factor XIIIa or markers of melanocytic, neural, or muscular differentiation. A diagnosis of Cowden syndrome was considered in one of the cases. These cases provide evidence that CD34 expression can occur in sclerotic fibromas, either solitary or associated with Cowden syndrome. When diagnosing a sclerotic fibroma, one should comment in the report regarding the possibility of Cowden syndrome.

Differential expression of CD34 and Ki-M1p in pleomorphic fibroma and dermatofibroma with monster cells

Pleomorphic fibroma (PF) and dermatofibroma with monster cells (DFMC) are characterized by the presence of numerous cells with large atypical nuclei. Despite cytologic similarities, the two entities are likely to be unrelated, but their histogenesis is poorly understood. In this study, we examined six cases of PF and eleven cases of DFMC by immunohistochemistry using antibodies against vimentin, alpha-smooth muscle actin, S-100 protein, CD34, factor XIIIa, and the pan-monocytic marker Ki-M1p. Strong vimentin expression was seen in all tumors, whereas none of them expressed S-100 protein. PF consistently exhibited CD34 staining but appeared to be depleted of Ki-M1p positive cells compared with the surrounding normal skin. Conversely, all cases of DFMC contained numerous Ki-M1p positive cells including atypical multinucleate cells, but virtually no CD34 reactivity was observed. A weak staining for alpha-smooth muscle actin was occasionally seen in a subset of the cells of both entities. Our results indicate that PF and DFMC are histogenetically distinct entities that may arise from two different types of dermal dendritic cells defined by their reactivity for CD34 and Ki-M1p, respectively. Immunohistochemistry using these two antibodies permits an easy and reliable discrimination between PF and DFMC.

A progression to dermatofibrosarcoma protuberans with a fibrosarcomatous component: a special reference to the chromosomal aberrations

Dermatofibrosarcoma protuberans (DFSP) with fibrosarcomatous areas (DFSP-FS) is differentiated from ordinary DFSP by its unfavourable prognosis. We carried out sequential analysis of numerical chromosomal abnormalities in two cases of DFSP during their progression to metastatic disease with FS areas (DFSP-M-FS). They were compared with nine cases of ordinary DFSP and three cases of DFSP-FS, but without metastases. Numerical chromosomal changes were examined by fluorescence in situ hybridization (FISH) using alpha-satellite centromeric probes for chromosomes 1, 8, 11 and 17. Numerical imbalances of chromosome 1 were not clarified. A gain of chromosome 8 was demonstrated in the two cases of DFSP-M-FS. A gain of chromosome 11 was observed in one of the two cases of DFSP-M-FS and in one case of DFSP-FS. A gain of chromosome 17 was demonstrated in both metastatic tumours and in recurrent tumours in two cases of DFSP-M-FS, in addition to two cases of DFSP-FS and four cases of ordinary DFSP with recurrent tumours or large tumours. This study raised the hypothesis that a gain of chromosome 17 developed in recurrent or large-sized DFSP, which occurs in high-risk groups with the possibility of a progression to FS.

Histopathologic and immunohistochemical diagnosis of benign and malignant fibrous and fibrohistiocytic tumors of the skin

This article describes the histopathology and immunohistochemistry of benign and malignant fibrous and fibrohistiocytic tumors. Some of the benign fibrohistiocytic proliferation's have atypical variants which could be misinterpreted as malignant processes. Key points for the diagnosis of these entities based on routine histology and immunohistochemistry are presented.

The pathological distinction between "deep penetrating" dermatofibroma and dermatofibrosarcoma protuberans

In selected cases, the clinicopathological distinction between deep penetrating dermatofibroma (DPDF), which involves the subcutis, and dermatofibrosarcoma protuberans (DFSPs) may be challenging. In most instances, attention to the cytological constituency of the lesions and the overall architecture is sufficient to make this separation. DPDF is typified by cellular heterogeneity, including giant cells and lipidized histiocytes; when it extends into the hypodermis, it does so either using the interlobular subcuticular fibrous septa as scaffolds or in the form of broad pushing fronts of tumor. In contrast, DFSP is a cytologically monotypical tumor, which entraps subcutaneous adipocytes diffusely or grows in stratified horizontal plates in the hypodermis. In the minority of cases where conventional morphological analysis of optimal biopsy specimens is diagnostically indeterminate, immunostaining for CD34 and factor XIIIa (FXIIIa) is helpful; it is also often necessary when a poorly-representative sample of the lesion has been obtained by the clinician. Characteristically, DF is diffusely FXIIIa-reactive and CD34-negative, whereas DFSP manifests the converse of those findings. Other markers such as Ki-M1p, mutant p53 protein, and metallothionein may also provide adjuvant diagnostic information in this context, as may the observation of abnormalities in chromosomes 17 and 22 by direct karyotypic analysis.

Bednar tumor (pigmented dermatofibrosarcoma protuberans) occurring in a site of prior immunization: immunochemical findings and therapy

Bednar tumor is a rare pigmented variant of dermatofibrosarcoma protuberans (DFSP). Because of its rarity, information is lacking regarding the optimal therapy and potential utility of immunohistochemistry in diagnosis. We report a case of Bednar tumor in which the diagnosis was aided by immunohistochemistry for CD34, an antigen known to be expressed in DFSP but not previously reported in Bednar tumor. Our case was also striking because it represents the first reported appearance of a Bednar tumor at a site of prior immunization, a phenomenon previously noted in some cases of DFSP. The patient was treated effectively with Mohs surgery and is without recurrence at 9 months.