CD34 immunoreactivity distinguishes between scar tissue and residual tumor in re-excisional specimens of dermatofibrosarcoma protuberans

Dermatofibrosarcoma Protuberans in Children

OPINION STATEMENT

Paediatric dermatofibrosarcoma protuberans (DFSP) is a rare soft tissue malignant tumour which displays aggressive local behaviour and has low metastatic potential. The diagnosis is often delayed as DFSP is usually mistaken for other skin conditions, particularly in the early stages of disease. DFSP tends to follow an indolent course after the initial presentation with what is often described as a "rubbery lump". As the disease progresses, the lump tends to enlarge, change colour, and exhibit a more nodular consistency. In rare cases, DFSP can present as an ulcerated exophytic lesion or a depressed area of skin, making diagnosis even more challenging. A high index of suspicion is warranted for early diagnosis, and referral to a specialist unit with expertise in both oncologic resection and reconstruction. DFSP tumours arise from the dermis and grow with finger-like projections. Therefore, in cosmetically sensitive or functionally important locations, an excision and analysis technique that assesses all excision margins is the gold standard of care. Slow Mohs technique performed with en bloc excision is a well-tolerated option for oncologic resection of the tumour. Mohs technique can also be considered but can be challenging in children for reasons explained below. As an alternative, depending on the anatomical location, tumours can be excised with a wide local excision. While an excision technique that incorporates the deep fascia with a 3-cm peripheral margin is acceptable in adults, planning of the excision margin in children should involve consideration of preoperative imaging with MRI, site of the tumour, age, and physical built of the child. Patients should be offered all treatment options considering the local outcomes, available expertise, and cost. A multidisciplinary approach and good communication between team members is crucial. Close collaboration with a pathologist who is familiar with sectioning technique that allows margin control is of paramount importance. Soft tissue reconstruction should be performed immediately after oncologic clearance, although a staged approach may be required. Adjuvant radiotherapy should be avoided in children due to the long-term risk of secondary malignancies and potential for growth disruption.

Hypertrophic and keloid scars fail to progress from the CD34- /α-smooth muscle actin (α-SMA)+ immature scar phenotype and show gradient differences in α-SMA and p16 expression

BACKGROUND

Our understanding of the pathogenesis underlying keloid scar formation is still very limited, and the morphological distinction between hypertrophic and keloid scars remains difficult.

OBJECTIVES

To test whether hypertrophic and keloid scars may reflect an inability to progress from immaturity to the desired mature normotrophic scar phenotype.

METHODS

Using whole-biopsy imaging and an objectively quantifiable way to analyse immunoreactivity, we have compared the immunohistopathological profiles of young immature scars with mature normotrophic scars, hypertrophic scars, and keloids with their surrounding-normal-skin.

RESULTS

Abnormal scars (hypertrophic scars and keloids) maintain the immature scar phenotype, characterized by a CD34^- (tumour biomarker) and α-smooth muscle actin (α-SMA)⁺ (myofibroblast) dermal region. This is in contrast to normal skin, surrounding-normal-skin and mature normotrophic scars that were CD34⁺ / α-SMA^- . Immature, hypertrophic and keloid scars showed abnormal epidermal differentiation (involucrin), but only hypertrophic scars and keloids showed increased epidermal thickness. Immature scars did show increased epidermal and dermal proliferation (Ki67), which was absent from abnormal scars, where mesenchymal hypercellularity (vimentin) and senescence (p16) were predominant. Keloidal collagen and α-SMA were previously considered to distinguish between hypertrophic scars and keloids. However, α-SMA staining was present in both abnormal scar types, while keloidal collagen was present mostly in keloids. There were no obvious signs of heterogeneity within keloid scars, and the surrounding-normal-skin resembled normal skin.

CONCLUSIONS

Both abnormal scar types showed a unique CD34^- /α-SMA⁺ /p16⁺ scar phenotype, but the differences between hypertrophic scars and keloids observed in this study were of a gradient rather than absolute nature. This suggests that scar progression to the mature normal scar phenotype is, for as yet unknown reasons, hindered in hypertrophic and keloid scars. What's already known about this topic? Hypertrophic and keloid scars both have sustained epidermal barrier dysfunction, suggesting the persistence of an immature scar phenotype. Morphological distinction between hypertrophic and keloid scars remains a topic of debate, although α-smooth muscle actin (α-SMA) and keloidal collagen have been considered distinguishing features of hypertrophic and keloid scars, respectively. It has been suggested that keloids are not simply homogeneous growths, as heterogeneity within keloid scars and possible involvement of the surrounding-normal-skin have been reported. What does this study add? An extensive whole-biopsy imaging and quantifiable immunohistochemical assessment of immature, mature normal, hypertrophic and keloid scars, including normal skin surrounding keloids. Hypertrophic and keloid scars maintain dermal characteristics of immature scars, rather than transitioning into the normal mature phenotype. Differences between hypertrophic and keloid scars were of a gradient rather than absolute nature, with keloids showing the more extreme phenotype. There was no obvious heterogeneity within keloids, and the normal skin surrounding keloids resembled normal skin. What is the translational message? Keloids remain primarily a clinical diagnosis. A raised scar with the CD34^- /α-SMA⁺ /p16⁺ phenotype with strong immunoreactivity for p16 and significant amounts of keloidal collagen, together with a thickened and strongly abnormal involucrin-stained epidermis, would sway the diagnosis towards keloid scars. A hypertrophic scar seems more likely when the CD34^- /α-SMA⁺ /p16⁺ phenotype shows very strong presence of α-SMA⁺ in large dermal nodules, with lesser p16 staining and absent or negligible keloidal collagen.

PDGFB Rearrangements in Dermatofibrosarcoma Protuberans of the Vulva: A Study of 11 Cases Including Myxoid and Fibrosarcomatous Variants

Dermatofibrosarcoma protuberans (DFSP) is a low-grade fibroblastic sarcoma that tends to arise in young to middle age adults and involve the trunk and proximal extremities. Rare examples of vulvar DFSP have been reported, including myxoid, myoid, and fibrosarcomatous variants, but detection of the characteristic t(17;22)(q22;q13) that produces COL1A1-PDGFB gene fusion has not been evaluated in a large series of primary vulvar tumors. The clinical, morphologic, immunohistochemical, and molecular cytogenetic features of 11 cases were examined. Patient age ranged from 29 to 75 yr (mean, 46 yr; median, 43 yr). Seven tumors were purely classic DFSP, 1 was purely myxoid DFSP and the remaining 3 had varying quantities of fibrosarcomatous DFSP. All cases of classic DFSP had diffuse expression of CD34 and low-level p53 immunoreactivity. Myxoid variants had strong, but reduced expression of CD34. Fibrosarcomatous DFSP showed focal CD34 expression and increased p53 reactivity. Nine of 11 tumors (82%) had rearrangement of PDGFB by fluorescence in situ hybridization. The 2 nonrearranged tumors were a classic DFSP and a myxoid DFSP with fibrosarcomatous transformation. Follow-up was available for 9 patients (82%) and ranged from 1 to 108 mo (mean, 30 mo; median, 21 mo). Eight patients had tumors with positive margins, one of which developed local recurrence after no further therapy. No patient developed metastasis. The high frequency of PDGFB rearrangement in vulvar DFSP provides a useful exploit in diagnostically challenging cases and genetic evidence of probable clinical response to targeted therapeutics in cases of locally advanced or metastatic tumors.

Guidelines for Diagnosis and Treatment of Cutaneous Sarcomas: Dermatofibrosarcoma Protuberans

Sarcomas comprise a broad group of tumors, many of whose biological behavior and aggressiveness differ from one type to another. The therapeutic approach is generally multidisciplinary and often complex. Developments in surgical and oncological dermatology during the last few decades have positioned dermatologists as specialists in the diagnosis and treatment of skin cancer. The aim of this article is to review the main soft tissue sarcomas that typically affect the skin. Dermatofibrosarcoma protuberans is a low-grade malignant sarcoma. It exhibits slow-growth, is locally invasive, and has low metastatic potential (<3%). Mohs micrographic surgery is the treatment of choice. The COL1A1-PDGFB translocation should be analyzed in cases of unclear diagnosis and when it is necessary to identify candidates for tyrosine kinase inhibitors. Imatinib is indicated for the treatment of locally advanced and metastatic dermatofibrosarcoma protuberans.

Clinicopathological features of dermatofibrosarcoma protuberans

Dermatofibrosarcoma protuberans (DFSP) is a superficial cutaneous tumor of low malignant potential characterized by a high rate of local recurrence. The histopathological appearance shows uniform spindle neoplastic cells arranged in a predominantly storiform pattern, typically with positive staining for cluster of differentiation (CD)34 and vimentin on immunohistochemistry. A minority of cases of DFSP have areas of sarcomatous transformation. Wide surgical excision is the cornerstone of treatment for DFSP. The objective of the present study was to determine the clinicopathological features of DFSP. Pathological records were searched for cases of DFSP in the database of the Department of Pathology, Faculty of Medicine Ramathibodi Hospital (Mahidol University, Bangkok, Thailand) between 1994 and 2013. The results showed 68 cases with DFSP. The mean age at diagnosis was 40 years (range, 3-86 years). Among this group of patients, 26 cases (38.2%) experienced local recurrence and 6 (8.8%) exhibited sarcomatous transformation of DFSP. The factors that predict the recurrence of DFSP are an incorrect first pathological diagnosis and an inadequate surgical margin. The factors that predict the sarcomatous transformation of DFSP are a larger tumor size and an incorrect first pathological diagnosis. In patients who have tumors with spindle cells arranged in a storiform pattern, CD34 immunohistochemical staining provides the definitive diagnosis. Exact histopathological categorization is important to select the appropriate treatment and predict the clinical outcome.

Congenital Dermatofibrosarcoma Protuberans: A Case Report and Literature Review

Congenital dermatofibrosarcoma protuberans (DFSP) is an extremely rare skin tumor that is commonly misdiagnosed, or is often diagnosed long after the initial presentation. Although many cases of DFSP are diagnosed in adulthood, there are some differences between adult DFSP and congenital DFSP. We report a case of congenital DFSP that was initially misdiagnosed as a simple vascular lesion. The delay in diagnosis led to the considerable growth of the lesion, such that a huge scar was left after the surgical treatment. The major differences between adult and congenital DFSP are discussed through a literature review. Clinicians should be aware of the characteristics of congenital DFSP, to reduce misdiagnosis and the delay of diagnosis from the initial presentation.

Bednar Tumor: A Report of Two Cases

We have recently treated two Japanese with Bednar tumor, pigmented dermatofibrosarcoma protuberans. The tumors were multilobular with brown-pigmentation and an irregular surface. Firm nodules were growing into the deep subcutaneous tissue, but they were movable over the underlying tissue. Histopathological examination and immunohistochemical studies showed the typical features of Bednar tumor and positive staining for CD34, which is known to be expressed in dermatofibrosarcoma protuberans. Bednar tumor is thought to be a variant of dermatofibrosarcoma protuberans and to have intermediate malignancy.

Uncommon cutaneous neoplasms of the head and neck

This article concentrates on the less-common cutaneous malignancies such as merkel cell, atypical fibroxanthoma, malignant fibrous histiocytoma, dermatofibrosarcoma protuberans, microcystic adnexal carcinoma, and sebaceous carcinoma. The clinical and histopathologic descriptions of each, most current and emerging etiologies, diagnosis, staging, treatment, and prognosis are discussed.

[Long-term experience with multidisciplinary therapy of twenty-six patients with dermatofibrosarcoma protuberans]

Dermatofibrosarcoma protuberans is a low or moderate grade malignant, uncommon soft tissue tumor. The tumor is characterized by slow, but locally aggressive growth, low metastatic potential and high recurrence rate. Initial treatment is the radical surgical excision, using traditional wide excision or Mohs surgery. In case of positive surgical margin or local recurrence, radio-chemotherapy and recently imatinib mesylate is used as adjuvant therapy.

AIMS

Twenty-six patients treated multidisciplinary for dermatofibrosarcoma protuberans were followed up.

METHODS AND RESULTS

Mean age of the patients was 44.7 years; mean follow-up time was 60.57 months. In fifteen cases (57.7%) R0 resection was performed, while eleven patients (42,3%) received only R1 resection. An average of 1.87 resections was necessary in order to achieve R0 resection. Six patients (23%) received adjuvant radiotherapy and two patients (7.6%) adjuvant chemotherapy following the removal of the primary tumor. Sixteen patients had no local recurrence. Ongoing treatments were needed in the case of ten patients (38.4%) who developed local recurrence. One patient has deceased due to distant metastases. Using statistical methods we examined the effects indicated as prognostic factors in the literature on local recurrence, precisely, the effect of age above 50 years and surgical radicalism.

CONCLUSIONS

Dermatofibrosarcoma protuberans can be successfully treated with multidisciplinary therapy. A larger number of cases and randomized multicenter investigations are needed in order to reach more accurate conclusion.

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.

Nonmelanoma skin cancer of the head and neck I: histopathology and clinical behavior

Non-Melanoma skin cancer (NMSC) is the most commonly encountered malignancy in almost every area of practice, but the cases that present to an Otolaryngology practice will be advanced in nature. The major subtypes of NMSC include basal cell carcinoma, squamous cell carcinoma, dermatofibrosarcoma protuberans, merkel cell carcinoma, and adnexal malignancies. In this review, we present the epidemiology, histology, clinical presentation and management of these major subtypes. Further, we present background on multimodality treatment for NMSC lesions that have become metastatic from their primary site and an introduction to the behavior and treatment of NMSC lesions in patients who have received organ transplants. Understanding the clinical behavior of advanced NMSC is essential knowledge for a general Otolaryngologist.

Dermatofibrosarcoma protuberans in childhood and adolescence: report of eight patients

We reviewed all occurrences of dermatofibrosarcoma protuberans in children under 17 years of age who were evaluated at Sainte-Justine Hospital, a tertiary-care pediatric center, between 1980 and 2002. The medical records and histologic features of all were reviewed. Eight patients were identified, three boys and five girls. The interval between apparent onset and diagnosis ranged from 3 months to 14 years. All lesions except one were removed by surgical excision with a margin of 1.5 to 3 cm including underlying fascia or by Mohs technique. Follow-up ranged from 2 to 15 years with median of 5 years. To date all the patients are alive and none has had a recurrence.

Application of immunohistochemistry to soft tissue neoplasms

CONTEXT

Soft tissue tumors are composed of numerous and complex diagnostic entities. Because of this complexity and the recognition of an intermediate malignancy category including some tumors with a deceptively bland histologic appearance, soft tissue tumors may represent a major diagnostic challenge to the general practicing pathologist.

OBJECTIVE

To correctly diagnose soft tissue tumors with the ancillary use of immunohistochemistry.

DATA SOURCES

Review of the current literature with emphasis on those tumors for which immunohistochemistry has proven to be particularly useful.

CONCLUSIONS

Immunohistochemistry plays an important role in the diagnosis of soft tissue tumors. One of its major utilities is to correctly identify a tumor as being of mesenchymal or nonmesenchymal origin. Once mesenchymal origin has been established, histologic subtyping according to specific cell lineage may be achieved with the use of lineage-specific markers. Tumors of uncertain cell lineage and tumors with primitive small round cell morphology are often characterized by a unique immunohistochemical phenotype. In this group of tumors, immunohistochemistry is most widely applied and is of greatest value. Despite the rapid development of molecular genetic techniques, immunohistochemistry still remains the most important diagnostic tool in the diagnosis of soft tissue tumors aside from recognition of morphologic features and clinical correlation.

Dermatofibrosarcoma protuberans at the site of a central venous line. Case report

Dermatofibrosarcoma protuberans (DFSP) is a locally aggressive cutaneous tumor that usually does not metastasize. Clinically, it may present as a reddish macule to protuberant nodule affecting the trunk and proximal extremities of young and middle-aged adults. Histologically, it is characterized by a monomorphous storiform proliferation of spindle cells, involving the dermis and hypodermis, with a honeycomb pattern of infiltration of the subcutaneous fat. In case of difficulty in diagnosis, immunohistochemical markers (especially CD34) are highly sensitive for DFSP. It is important to remember that the rarity of DFSP, its resemblance to hypertrophied scars and keloids, and its appearance at trauma sites sometimes make the diagnosis of DFSP difficult and delayed. In the literature, DSFP was not described in a child until 1957. Here we report an instance of DFSP at an unusual site in a 9-year-old child, which was the location of a previous central venous line insertion in the left supraclavicular area. A complete excision of the tumor with a wide surgical margin of 3cm of visibly uninvolved tissue was performed, followed by a deltopectoral flap and skin split graft. Postoperatively, the patient's general condition was stable and he was discharged after 5 days to be followed up 3 months later in our clinic.

Modified Mohs micrographic surgery in the therapy of dermatofibrosarcoma protuberans: analysis of 22 patients

BACKGROUND

Dermatofibrosarcoma protuberans (DFSP) is a very rare, low-grade malignant tumor. Local recurrence is frequent after incomplete resection either because of false diagnosis or inadequate standard surgical excision. This study evaluated the clinical outcome of micrographic surgery with paraffin sectioning in the therapy of DFSP.

METHODS

Medical charts of 22 patients with histologically confirmed DFSP treated at our institution between 1987 and 2002 were reviewed.

RESULTS

For 13 patients with primary and 9 with recurrent disease, tumor-free excision margins could be achieved, and all patients remained free of local recurrence during a mean follow-up of 54 months.

CONCLUSIONS

The results of our study and a review of the literature confirm the successful and recurrence-free treatment of DFSP with micrographic surgery as the treatment of choice for this locally invasive tumor. Particularly in recurrent lesions, we recommend the use of paraffin sectioning and three-dimensional histological evaluation as an accurate additional tool for treatment optimization.

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).

A light microscopic and immunohistochemical evaluation of scars

BACKGROUND

Scars are commonly encountered by dermatopathologists and usually do not present a diagnostic challenge. However, in some cases, the pathologist may need to consider a broad differential diagnosis including fibrohistiocytic tumors, smooth muscle tumors, myofibroblastic proliferations and desmoplastic malignant melanoma. Although specific histologic aspects of scars have been well studied, a complete histochemical profile of scars, especially at various stages of evolution, has not been described.

METHODS

Twenty-five cases of scars including 8 normal scars, 5 hypertrophic scars and 12 keloids were studied. Sections were examined with Verhoeff van Giesson, colloidal iron, Giemsa, smooth muscle actin (SMA), CD34, Factor XIIIa and S-100.

RESULTS

All scars were negative for CD34 expression. Factor XIIIa immunostaining identified only rare dermal dendrocytes. S-100 was absent in 23 of 25 cases and stained scattered cells (less than 10%) in the other 2 cases. SMA was positive in 14 of 25 cases with 6 of these showing staining of up to 50% of spindled cells. Elastic fibers were markedly reduced or absent in all cases, mucin showed moderate or marked staining in three-fourths of the cases and dermal mast cells showed a moderate increase in 5 cases.

CONCLUSIONS

These findings confirm prior reports that negative staining with CD34, Factor XIIIa and S-100 can help differentiate scars from dermatofibrosarcoma protuberans, dermatofibroma and desmoplastic malignant melanoma, respectively. SMA staining is much more variable and requires careful interpretation.

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.

Congenital and childhood dermatofibrosarcoma protuberans: a case report and review of the literature

Dermatofibrosarcoma protuberans (DFSP) occurs most commonly on the trunk, affects all races, and often develops between the second and fifth decades of life. It is uncommon in childhood and is sometimes mistaken for a vascular lesion, as it often presents as a blue macule or small nodule. Review of the English literature revealed approximately 152 cases of DFSP developing before 16 years of age and only 19 claimed congenital cases. A case of congenital dermatofibrosarcoma protuberans is presented with a literature review and discussion of congenital and childhood presentations of the tumor.

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.

Immunohistochemistry in diagnostic dermatopathology

This article briefly reviews many immunohistochemical stains that have been in use for years, emphasizing their diagnostic use and potential pitfalls. Several newer immunostains are described in a more comprehensive fashion, including brief summaries from recently published studies.

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.

Pretreatment with intralesional hyaluronidase prior to excision of dermatofibrosarcoma protuberans

Dermatofibrosarcoma protuberans (DFSPs) are an uncommon malignancy that commonly recur, but rarely metastasize. The origin of DFSPs is controversial; however, they stain with the progenitor marker CD34. DFSPs usually show increased stromal mucin, mainly hyaluronic acid (HA). HA increases cellular proliferation, delays differentiation and increases cellular motion. We evaluated the pretreatment of DFSPs with intralesional injections of hyaluronidase (HD) prior to the surgical excision. Five of nine cases of DFSPs were pretreated with HD. In HD-pretreated cases the margins for excision of the residual tumor were reduced. HD pretreatment also decreased CD34 staining and increased polarizable collagen in the residual tumor.

Immunohistochemical characterization of dermatofibrosarcoma protuberans with practical applications for diagnosis and treatment

Dermatofibrosarcoma protuberans (DFSP) is a rare, clinically challenging, soft tissue tumor. The main histologic differential of DFSP is usually a dermatofibroma. In 1990, the first report appeared demonstrating that cells of DFSP express the human progenitor antigen CD34 on their surface. Since then, there have been increasing reports of the usefulness of immunohistochemical staining with CD34 to differentiate DFSP from dermatofibroma and other soft tissue tumors. This literature is reviewed with special emphasis on the insights studies have provided into the histogenesis of DFSP. The literature demonstrating the practical applications of CD34 staining in the diagnosis and treatment of DFSP is also discussed.

The role of radiotherapy in the local management of dermatofibrosarcoma protuberans. Soft Tissue Tumours Working Group

Dermatofibrosarcoma protuberans (DFSP), a fibrohistiocytic tumour of intermediate malignancy, has a strong tendency to recur locally. Wide local excision is the recommended treatment modality. A retrospective analysis was performed on 38 consecutive DFSP patients presenting to The Netherlands Cancer Institute, to define the role of radiotherapy. Of the 21 patients treated surgically (all with negative resection margins) seven recurred, a local control probability of 67%. Combined modality treatment was given to 17 patients. Prior to radiotherapy, these patients experienced 33 occurrences of DFSP, but after irradiation only three recurrences were seen, a local control probability of 82%. These results are in keeping with the recent literature where increasing value is being given to both adjuvant and curative radiotherapy in the local management of DFSP. We recommend radiotherapy in DFSP patients where repeated surgery may cause mutilation or functional impairment.

Dermatopathologic advances in clinical research. The expression of antibody to CD34 in mucocutaneous lesions. off

The human progenitor cell antigen, CD34, is selectively expressed in most hematopoietic colony-forming cells from normal human bone marrow, and in a significant proportion of acute leukemias. Within the dermis, CD34 is normally expressed by endothelial cells, dendritic cells, and the spindle-shaped cells around adnexal structures. Benign and malignant vascular lesions, adnexal tumors differentiating toward the external root sheath (trichilemmomas and pilar tumors), specific benign soft tissue tumors (spindle cell lipoma and solitary fibrous tumors), and many of the gastrointestinal stromal tumors uniformly express CD34 antigen. CD34 expression is also often present in benign tumors of neural origin; however, it is less consistently present in malignant peripheral nerve sheath tumors.

Dermatofibrosarcoma protuberans

BACKGROUND

Dermatofibrosarcoma protuberans (DFSP) is a locally aggressive soft tissue sarcoma in which recurrences are common. It usually affects middle-aged individuals with the most common location being the trunk. Sex distribution varies among published series. Mohs surgery is the treatment of choice. Immunostaining for CD34 facilitates the diagnosis of DFSP and aids in indicating the surgical margins of the tumor; however, the sensitivity of this marker is variable.

MATERIALS AND METHODS

This is a retrospective review of 16 cases of DFSP treated with Mohs surgery at Duke University Medical Center between 1981 and 1994. Clinical and histologic features are analyzed. Immunohistochemical stains for CD34 were performed in one case.

RESULTS

Twelve of the 16 patients were women with four younger than 20 years. The most common location was the trunk. No recurrences following Mohs surgery have been documented. The average number of stages during Mohs surgery was 3.3. Surgical wounds were repaired by complex layered closure in 11 cases. Stains for CD34 were negative on the initial biopsy, but were positive on frozen sections.

CONCLUSIONS

Both sexes and all age groups are affected by DFSP. Mohs surgery is the treatment of choice and offers a significant improvement in cure rates with the cosmetic advantage of smaller postoperative wounds. Immunostains for CD34 appear to be an important adjunct to facilitate tumor removal, but the variable expression of CD34 antigen by DFSP tumors can lead to variable staining patterns.

Dermatofibrosarcoma protuberans

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

CD34-reactive fibrous papule of the nose

In human skin, the CD34 antigen is expressed on endothelium, periadnexal cells, and a population of reticular dermal interstitial cells. CD34 expression is characteristic of dermatofibrosarcoma protuberans and several other neoplasms, but not of typical fibrous papules of the nose. We describe a 16-year-old white girl with a slowly growing papule on the nose. Histopathology showed a dermal tumor with a superficial component of branched, thin-walled blood vessels and a deeper component of benign-appearing, spindle-shaped cells. These cells uniformly and strongly expressed CD34, but not factor XIIIa or markers of melanocytic, neural, muscular, vascular, or histiocytic differentiation. We consider this lesion a CD34-reactive fibrous papule. This benign tumor must be clearly distinguished from dermatofibrosarcoma protuberans, which also is composed of bundles of CD34-reactive spindle-shaped cells in most cases but has locally aggressive behavior.

Immunohistochemistry in diagnostic dermatopathology

Immunopathology continues to be important in diagnostic dermatopathology. Immunopathology is an invaluable tool for assessing the tissue of origin or direction of differentiation of cells. In some cases this can result in a more precise diagnosis. This article reviews the role of immunopathology in determining the biologic behavior of hematolymphoid infiltrates. It explores the methodology of immunoperoxidase, discusses the most commonly used antibody reagents, and presents a series of diagnostic dilemmas in which immunopathology can be useful. In each case a strategy is established that maximizes the likelihood of making a definitive diagnosis.

A fresh morphological and functional look at dermal dendritic cells

During the past decade, a group of cells located in the dermis and possessing a dendritic morphology have emerged from obscurity and become recognized as important members of the "dermal immune system". This group of cells is characterized by a considerable degree of immunophenotypic and functional heterogeneity. In this review, the salient features of these dermal dendritic cells are put into a dermatopathology perspective, with particular emphasis on a broad group of inflammatory and neoplastic skin diseases. There appear to be multiple subsets of dermal dendritic cells, and 17 different conditions linked to active participation of these newly recognized cells. Exactly how these different subsets of dermal dendritic cells interact amongst each other, as well as with adjacent cells such as T-lymphocytes, endothelial cells, fibroblasts, and keratinocytes in these different diseases is unclear at this time. However, isolation techniques and monoclonal antibodies capable of distinguishing these subsets, as well as functional assays, are currently available and will permit definitive conclusions to be drawn regarding their pathophysiological significance. It is highly likely that, as more data is gathered, dermal dendritic cells will be the focus of further investigative activity by dermatopathologists for the next decade, and well past the year 2000.

Merkel cells are integral constituents of desmoplastic trichoepithelioma: an immunohistochemical and electron microscopic study

The incidence of Merkel cells has previously been investigated in a number of inflammatory and tumorous lesions of the skin. Special attention was given to tumors with follicular differentiation. In the present study we examined the localization of Merkel cells in another adnexal tumor, the desmoplastic trichoepithelioma (n = 15), as well as in its main differential diagnosis, the morpheiform basal-cell carcinoma (n = 30). Using immunohistochemical methods, we found Merkel cells as a stable constituent in desmoplastic trichoepitheliomas, but failed to detect them in morpheiform basal-cell carcinomas. These findings might therefore be an important tool in the sometimes very difficult but clinically imperative distinction between these two conditions. Furthermore, our study may be of interest in the discussion about the origin of desmoplastic trichoepitheliomas. High numbers of Merkel cells in desmoplastic trichoepitheliomas indicate a bulge-derived origin of this adnexal tumor, since high numbers of Merkel cells, especially in the bulge, were recently discovered. Although the significance of Merkel cell hyperplasia in desmoplastic trichoepithelioma is not presently understood, a regulatory role of the Merkel cell in growth and development of this adnexal tumor is suggested.