Immunohistochemistry in the diagnosis of soft tissue tumours

Immunohistochemistry is particularly important in the field of soft tissue tumours because of their variety and the frequent difficulty of diagnosis. The first part of this paper discusses useful or new antibodies, together with others that are no longer of use. The second part is devoted to the role of immunohistochemistry in the diagnosis of soft tissue tumours: identification of some rare or atypical benign lesions, identification of non-mesenchymal malignant tumours, and classification of sarcomas. The respective roles of immunohistochemistry and molecular biology are underlined.

A subgroup of malignant fibrous histiocytomas is associated with genetic changes similar to those of well-differentiated liposarcomas

Increasing clinical and pathological evidence suggests that malignant fibrous histiocytomas (MFH) comprise a heterogeneous tumor group. In a series of 108 MFH tested by comparative genomic hybridization, we found in 22 tumors high-level coamplification of the 12q14 approximately q15 chromosome region with other loci, a genetics strongly reminiscent of what has been observed for well-differentiated liposarcomas. Nevertheless, these MFH differ from liposarcomas by a high recurrence of coamplified partners because coamplified loci were seen at 1p32 in nine cases, 6q23 in seven cases, and 12q24 in six cases. The same recurrence was observed in a series of dedifferentiated liposarcomas, but not in a series of well-differentiated liposarcomas. These observations demonstrate that a subgroup of MFH share a genetic partner very similar to that observed in liposarcomas, and suggest that the undifferentiated status of these tumors is closely related to the amplifications of specific chromosome loci.

Newly described adipocytic lesions

This article reviews the clinicopathologic features and differential diagnoses of 7 newly described adipocytic lesions: chondroid lipoma, myolipoma, lipomatous hemangiopericytoma, sclerotic lipoma, fibrohistiocytic lipoma, hemosiderotic fibrohistiocytic lipomatous lesion, and spindle cell liposarcoma. Two recently described variants of spindle cell/pleomorphic lipoma are also presented: the pseudoangiomatous variant and the dendritic fibromyxolipoma, which corresponds in all likelihood to a peculiar myxoid variant of spindle cell lipoma.

Newly described adipocytic lesions

This article reviews the clinicopathologic features and differential diagnoses of 7 newly described adipocytic lesions: chondroid lipoma, myolipoma, lipomatous hemangiopericytoma, sclerotic lipoma, fibrohistiocytic lipoma, hemosiderotic fibrohistiocytic lipomatous lesion, and spindle cell liposarcoma. Two recently described variants of spindle cell/pleomorphic lipoma are also presented: the pseudoangiomatous variant and the dendritic fibromyxolipoma, which corresponds in all likelihood to a peculiar myxoid variant of spindle cell lipoma.

A well-differentiated liposarcoma with a new type of chromosome 12-derived markers

Well-differentiated liposarcomas (WDLPS) are cytogenetically characterized by the presence of supernumerary ring or giant rod marker chromosomes. These supernumerary chromosomes are composed of amplified sequences from chromosome 12 (12q14 approximately 15) in association with amplified segments from various other chromosomes, and contain alterations of the alpha satellite sequences. We report a case of WDLPS of the lipoma-like and sclerosing subtype that contains a novel type of supernumerary marker chromosome. Instead of rings or giant rods, these cells had three apparently identical copies of a subtelocentric supernumerary marker with a size and shape similar to C-group chromosomes. Fluorescence in situ hybridization analysis revealed that the markers were composed of amplified material from 12q14 approximately 15, including the genes MDM2 and CDK4. Similar to the rings and giant rods observed in other WDLPS cases, these unusual markers had no alpha satellite repeats at the primary constriction site, but centromeric activity could be demonstrated by using anti-centromere protein C antibodies. These findings show that the supernumerary markers of WDLPS may be variable in size and shape, but consistently share the same genomic structure, specifically 12q amplified sequences together with centromere alterations, and underline the importance of molecular methods in the diagnosis of adipose tissue tumors.

[Spindle cell lipoma and 13q deletion: diagnostic utility of cytogenetic analysis]

AIM

Spindle cell lipomas are rare adipose tissues tumors. Histologically, these lesions are composed of mature adipocytes and spindle cells associated with collagen bundles. Spindle cell lipomas are benign tumors that can be difficult to distinguish from malignant tumors such as spindle cell liposarcomas, myxoid liposarcomas or well-differentiated liposarcomas.

RESULTS

We report herein the description of two new cases. The first case was a deeply situated and infiltrating tumor located in the retromastoidian area. The karyotype showed the presence of two chromosomal abnormalities, a partial deletion of the long arm of chromosome 13, del(13)(q12) and a balanced reciprocal translocation t(2;6)(p16~21;p21). The second case was a subcutaneous tumor of posterior cervical localization. The karyotype showed a 13q deletion associated with a complex rearrangement of chromosomes 5, 6 and 10. The presence of the 13q deletion allowed us to confirm the diagnosis of spindle cell lipoma in both cases. This deletion has been previously described in six out the eleven published karyotype reports. The 13q deletion is usually associated with partial monosomy 16. The present case confirms that it can occur independently. The 6p21 rearrangement may also play a role in the pathobiology of this tumor, as suggested by the positive HMGIY expression detected by immunohistochemistry.

CONCLUSION

Our study further illustrates that spindle cell lipomas can infiltrate the surrounding muscle and emphasizes the usefulness of cytogenetic analysis in the differential diagnosis of soft tissue tumors.

[Standards, options and recommendations: practice guidelines for difficult diagnosis in surgical pathology or cytopathology in cancer patients]

CONTEXT

The "Standards, Options and Recommendations" (SOR) project, started in 1993 is a collaboration between the Federation of the French Cancer Centres (FNCLCC), the 20 French Cancer Centres and specialists from French Public Universities, General Hospitals and Private Clinics. The main objective is the development of clinical practice guidelines to improve the quality of health care and outcome for cancer patients. The methodology is based on literature review and critical appraisal by a multidisciplinary group of experts, with feedback from specialists in cancer care delivery.

OBJECTIVES

To develop clinical practice guidelines according to the definitions of the Standards, Options and Recommendations project for difficult diagnoses in surgical pathology or cytopathology in cancer patients.

METHODS

Data were identified by searching Medline and using the personal reference lists of members of the expert groups. Once the guidelines were defined, the document was submitted for review to 71 independent reviewers.

RESULTS

The main recommendations to prevent and reduce the number of difficult diagnoses in surgical pathology or cytopathology are: 1) The development of quality insurance programs with use of written procedures in each pathology laboratory (standard). 2) The knowledge of clinical data in order to explain surgical pathology or cytopathology results (standard). 3) The availability of complementary patient informations (radiologic data . . .) can be useful to explain surgical pathology or cytopathology results (option). The main recommendations to detect lesions associated with difficult diagnosis in surgical pathology or cytopathology are: 1) Tumor types known as potential difficult diagnosis in surgical pathology or cytopathology should be reviewed by a second pathologist. 2) The systematic second reviewing for every case is expensive but has to be done when the difficulty is know (sarcoma, lymphoma . . .) by experienced pathologists. The main recommendations to solve difficult diagnosis in surgical pathology or cytopathology are: 1) Block recuts, use of special techniques (immunocytohistochemistry and molecular biology), additional data from clinicians, second opinion by a local pathologist, or new specimen can be required for establishing the diagnosis (options). 2) Outside second opinion by expert pathologist has to be considered once the other steps did not allow to establish surgical or cytopathology diagnosis (recommendations, expert agreement).

Prognostic factors in retroperitoneal sarcoma: a multivariate analysis of a series of 165 patients of the French Cancer Center Federation Sarcoma Group

BACKGROUND

Surgery is the main prognostic factor in retroperitoneal sarcoma. However, despite progress, surgery alone is rarely curative, and analysis of the causes of failures and of other prognostic factors are warranted to ascertain treatment orientations.

METHODS

Data of patients treated from 1.80 to 12.94 for primary retroperitoneal sarcoma were extracted from the French Federation of Cancer Centers Sarcoma Group registry. Univariate and multivariate analysis were performed for initial local control and for local and general outcome. One hundred sixty-five patients (median age, 54 years; range, 16--82 years) were identified. Median tumor size was 15 cm (range, 2--70 cm); 31% of tumors presented with neurovascular or bone involvement. Liposarcoma, leiomyosarcoma, and malignant fibrous histiocytoma represented 66% of the tumors. Eighty-four percent of the tumors were of high or intermediate grade. Twenty patients had initial metastases. Multimodality treatment included surgery (150 patients), radiotherapy (92 patients), and chemotherapy (77 patients). Complete excision was achieved in 94 of 145 nonmetastatic patients. Median follow-up was 47 months (range, 3--160 months).

RESULTS

Actuarial overall 5-year survival rate (median) was 46% (51 months). The main prognostic factors for survival were initial metastases and surgery, which represented the major treatment-linked factor. High-grade of tumors affected local recurrence, metastatic recurrence, and survival. Adjuvant radiotherapy was significantly associated with reduced local recurrence. Various evolutive patterns were observed with histologic subtypes.

CONCLUSIONS

Aggressive surgery remains mandatory in retroperitoneal sarcoma, but a randomized trial is needed to evaluate the place of radiotherapy for local control.

[Skin location of multiple myeloma mimicking a vascular tumor]

INTRODUCTION

Cutaneous location of multiple myeloma is rare, and generally develops as a consequence of direct spread from an underlying bony focus of the disease. Metastatic skin lesions without adjacent bone involvement are uncommon. The prognosis is very poor.

CASE REPORT

A 74-year-old man consulted for a hemorrhagic cutaneous nodule localized on the left inguinal area. This patient had been treated for five months for a stage I IgG lambda multiple myeloma. The histopathologic examination of the lesion showed a predominantly nodular configuration made up of masses of atypical cells with numerous hemorrhagic areas. The diagnosis of cutaneous metastasis of multiple myeloma was confirmed by the positivity of the cells for anti-IgG lambda antibodies.

DISCUSSION

Cutaneous involvement in multiple myeloma without extension from underlying bony focus is exceptional. The lesions generally consist of firm, erythematous nodules involving the neck and lower extremities. To our knowledge, we present here the first case mimicking clinically and histologically a malignant vascular proliferation.

Predictive value of grade for metastasis development in the main histologic types of adult soft tissue sarcomas: a study of 1240 patients from the French Federation of Cancer Centers Sarcoma Group

BACKGROUND

Histologic grade is said to be the most important prognostic factor in adult soft tissue sarcomas (STS), but most grading systems have been tested in the overall sarcoma group and the predictive value of histologic grade needs to be assessed specifically for each of the histologic categories.

METHODS

From 1980 to 1994, 1240 nonmetastatic patients were entered in the French STS database. The following parameters were studied: patient's age and gender, previous history, tumor location, size and depth, neurovascular or bone involvement (NBI), histologic type and subtype, and grade (the French Federation of Cancer Centers [FNCLCC] system). Median follow-up for the survivors was 88 months; only 5% of patients were lost to follow-up. The authors performed univariate and multivariate analyses for metastasis-free survival for the overall sarcoma group and for every main histologic type.

RESULTS

In order of importance, parameters were respectively retained as independent predictors of metastasis as follows: grade, tumor size, NBI and tumor depth for the overall group, grade and NBI for malignant fibrous histiocytomas (n = 349), tumor size, histologic subtype and grade for liposarcomas (n = 188), NBI, grade and tumor size for leiomyosarcomas (n = 148), grade and NBI for synovial sarcomas (n = 125), grade for unclassified sarcomas (n = 140), and sarcomas of other types (n = 158). No parameter was significant for malignant schwannomas (n = 72) or for rhabdomyosarcomas (n = 60).

CONCLUSION

In this study, histologic grade appeared as an independent predictor of metastasis development in the main histologic types of adult STS, with the exception of malignant schwannomas and rhabdomyosarcomas.

Predictive value of grade for metastasis development in the main histologic types of adult soft tissue sarcomas: a study of 1240 patients from the French Federation of Cancer Centers Sarcoma Group

BACKGROUND

Histologic grade is said to be the most important prognostic factor in adult soft tissue sarcomas (STS), but most grading systems have been tested in the overall sarcoma group and the predictive value of histologic grade needs to be assessed specifically for each of the histologic categories.

METHODS

From 1980 to 1994, 1240 nonmetastatic patients were entered in the French STS database. The following parameters were studied: patient's age and gender, previous history, tumor location, size and depth, neurovascular or bone involvement (NBI), histologic type and subtype, and grade (the French Federation of Cancer Centers [FNCLCC] system). Median follow-up for the survivors was 88 months; only 5% of patients were lost to follow-up. The authors performed univariate and multivariate analyses for metastasis-free survival for the overall sarcoma group and for every main histologic type.

RESULTS

In order of importance, parameters were respectively retained as independent predictors of metastasis as follows: grade, tumor size, NBI and tumor depth for the overall group, grade and NBI for malignant fibrous histiocytomas (n = 349), tumor size, histologic subtype and grade for liposarcomas (n = 188), NBI, grade and tumor size for leiomyosarcomas (n = 148), grade and NBI for synovial sarcomas (n = 125), grade for unclassified sarcomas (n = 140), and sarcomas of other types (n = 158). No parameter was significant for malignant schwannomas (n = 72) or for rhabdomyosarcomas (n = 60).

CONCLUSION

In this study, histologic grade appeared as an independent predictor of metastasis development in the main histologic types of adult STS, with the exception of malignant schwannomas and rhabdomyosarcomas.

ALK probe rearrangement in a t(2;11;2)(p23;p15;q31) translocation found in a prenatal myofibroblastic fibrous lesion: toward a molecular definition of an inflammatory myofibroblastic tumor family?

A prenatal tumor located in the lumbar paravertebral area was discovered during a routine ultrasound examination at 32 weeks of pregnancy and surgically removed at 4 months of life. The histopathological diagnosis was first suggested to be an infantile desmoid fibromatosis. The tumor karyotype showed a three-way translocation involving both chromosomes 2 and a chromosome 11, t(2;11;2)(p23;p15;q31). Fluorescence in situ hybridization with a probe flanking the ALK gene at 2p23 demonstrated a rearrangement, as previously described in inflammatory myofibroblastic tumors (IMTs). In light of the genetic analysis, the histopathological diagnosis was revised to IMT, although inflammatory cells were scarce. IMTs are pseudosarcomatous inflammatory lesions that primarily occur in the soft tissue and viscera of children and young adults. Our report describes for the first time the occurrence of IMT during prenatal life. The ALK rearrangement may represent the molecular definition of a subgroup of mesenchymal tumors, not always with complete morphological features of IMT, similar to the model of EWS rearrangement in the Ewing sarcoma family of tumors.

Solitary fibrous tumour of the kidney

Solitary fibrous tumours are relatively rare neoplasms initially described in the pleura. Such lesions are now reported in many extrathoracic sites. To our knowledge, only 8 cases have been reported in the kidney. All these cases were benign. We report a patient with a solitary fibrous tumour of the kidney with infiltration of the wall of the renal vein. Microscopic examination showed proliferation of spindle cells with a prominent vascular haemangiopericytoma-like pattern. Hypercellular areas were admixed with hyalinized collagenous zones. The neoplastic cells stained for vimentin and CD34. CD31 was negative. Biologically, we did not find any arguments for malignancy: the flow cytometric study showed diploid histograms, and immunostaining for p53 was negative.

Leiomyosarcomas and most malignant fibrous histiocytomas share very similar comparative genomic hybridization imbalances: an analysis of a series of 27 leiomyosarcomas

Twenty-seven tumor samples with a diagnosis of leiomyosarcomas (LMS) were characterized by comparative genomic hybridization. The results were compared with immunohistochemical analysis of the smooth muscle profile of the tumors and expression of the RB1 gene protein. The comparative genomic hybridization profiles suggested that 7 of the 27 tumors might have been misclassified. High levels of DNA amplification were detected in 20 different small regions and recurrently involved bands 1p34, q21, 12q13-15, 17p, and 22q. Most recurrent simple gains were noted at sites such as 1p3, 1q21, 15q12-15, 16p, 17p and 17q, 19, 20q, 22q, and Xp. Significant losses of chromosome 13 were detected in 19 of the 27 tumors with a putative common region of loss in bands 13q14-21. Losses of chromosomes 1q, 2p and 2q, 4q, 9p, 10p and 10q, 11p and 11q23, and 16q were also highly recurrent. A comparative analysis between the most frequent genomic imbalances observed in this study of LMS and the genomic imbalances observed in a large proportion of malignant fibrous histiocytomas (MFH) from a previous study demonstrated that both types of tumors had similar recurrent imbalances. Although MFH were once thought to be a separate member of the soft tissue sarcoma family, our observations support the hypothesis that MFH are a morphologic modulation in the tumoral progression of other sarcomas, particularly LMS.

Prognostic factors in localized primary synovial sarcoma: a multicenter study of 128 adult patients

PURPOSE

To identify most significant and therapeutically relevant prognostic factors in adults with localized primary synovial sarcomas (SS) and to confirm the usefulness of the French Federation of Cancer Centers (FNCLCC) grading system, the prognostic impact of which has been already proven in soft tissue sarcomas.

PATIENTS AND METHODS

Data on 128 patients with nonmetastatic SS collected from a cooperative database by the FNCLCC Sarcoma Group between 1980 and 1994 were studied retrospectively. Immunohistochemistry was performed at diagnosis in 77 cases (61%). The tumors were classified as biphasic (n = 45), monophasic fibrous (n = 72), and poorly differentiated (n = 10) subtypes. Histologic grade was determined according to the FNCLCC method, and vascular invasion was assessed in every case.

RESULTS

The 5-year disease-specific survival (DSS) rate for this series of patients with localized SS was 62.9% (+/- 9.6% [SD]) with a median follow-up time of 37 months (range, 8 to 141 months). In multivariate analysis, the adverse risk factors associated with decreased DSS were International Union Against Cancer/American Joint Committee on Cancer stage III/IVA disease, male sex, and truncal tumor locations. For metastasis-free survival (MFS), disease stage III/IVA, tumor necrosis, and monophasic subtypes were the major factors associated with a less favorable prognosis. Separately, when not using disease stage, tumor necrosis, and mitotic activity, histologic grade became the most significant prognostic factor for both DSS and MFS. In addition, larger tumors and older patients become associated with a significantly worse prognosis. Independent adverse risk factors for local recurrence-free survival included histologic grade 3 and truncal tumor location.

CONCLUSION

These data confirm that not all SS present the same severe outcome. High-risk patients identified on the basis of these parameters may qualify for an aggressive treatment approach.

The detection of Tel-TrkC chimeric transcripts is more specific than TrkC immunoreactivity for the diagnosis of congenital fibrosarcoma

The t(12;15)(p13;q25) translocation, a recurrent chromosomal abnormality of congenital fibrosarcoma, leads to the expression of a Tel-TrkC fusion transcript. To determine whether detection of the chimeric protein may be helpful for the diagnosis of congenital fibrosarcoma, immunohistochemistry was performed with an anti-TrkC antibody on 26 spindle cell tumours of newborn or young children (n=19) or adults (n=7). Four out of five congenital fibrosarcomas showed TrkC immunoreactivity with cytoplasmic paranuclear staining. However, TrkC immunoreactivity was not restricted to congenital fibrosarcoma and was observed in infantile myofibromatosis, congenital haemangiopericytoma, desmoid tumour, nodular fasciitis, fibrous hamartoma, inflammatory myofibroblastic tumour, and adult fibrosarcoma. RT-PCR analysis was performed on nine cases, including four congenital fibrosarcomas, for which frozen material was available. Tel-TrkC transcripts were detected by RT-PCR in the four congenital fibrosarcomas analysed, but not in the five other spindle cell tumours. Furthermore, several Tel-TrkC transcripts encoding for kinase isoforms of the Tel-TrkC protein were detected in congenital fibrosarcoma and may be involved in oncogenesis. The reciprocal TrkC-Tel transcript was detected in only one congenital fibrosarcoma. While the detection of a Tel-TrkC fusion transcript is a recurrent feature of congenital fibrosarcoma, TrkC immunoreactivity does not appear specific for the diagnosis of fibromatous paediatric tumours.

The RB1 gene is the target of chromosome 13 deletions in malignant fibrous histiocytoma

Forty-four malignant fibrous histiocytomas (MFHs) were studied by comparative genomic hybridization. Among the observed imbalances, losses of the 13q14-q21 region were observed in almost all tumors (78%), suggesting that a gene localized in this region could act as a tumor suppressor gene and that its inactivation could be relevant for MFH oncogenesis and/or progression. We determined by CA repeat analyses a consensus region of deletion focusing on the RB1 region. The RB1 gene was then analyzed by protein truncation test, direct sequencing, fluorescence in situ hybridization, Southern blotting, and immunohistochemistry. RB1 mutations and/or homozygous deletions were found in 7 of the 34 tumors analyzed (20%). Among the 35 tumors with comparative genomic hybridization imbalances analyzed by immunohistochemistry, 30 (86%) did not exhibit significant nuclear labeling. The high correlation between chromosome 13 losses and absence of RB1 protein expression and the mutations detected strongly suggest that RB1 gene inactivation is a pivotal event in MFH oncogenesis. Moreover, the observation of a high incidence of MFH in patients previously treated for hereditary retinoblastoma fits well this hypothesis.

Characterization of centromere alterations in liposarcomas

Supernumerary ring and large marker chromosomes are a characteristic of atypical lipomas and well-differentiated liposarcomas (ALP-WDLPS) and are composed of amplified 12q14-15 sequences in association with variable segments from other chromosomes. Although stably transmitted, these chromosomes contain centromeric alterations, showing no detectable alpha-satellite sequences. We performed C-banding, fluorescence in situ hybridization, and immunostaining with anti-centromere antibodies in 8 cases of liposarcomas with supernumerary rings and large markers, including 5 ALP-WDLPS and 3 dedifferentiated-LPS and high-grade LPS. Our results with alpha-satellite probes and anti-CENPB antibodies confirm the lack of detectable alpha-satellite sequences in the five ALP-WDLPS supernumerary chromosomes, whereas centromeric activity was proved by the detection of kinetochores by using anti-CENPC antibodies. In contrast, the high grade and dedifferentiated liposarcomas showed a different pattern. In 2 cases, amplified chromosome 12 sequences, including amplification of alpha-satellite 12 sequences in 1 case, were present on chromosomes with typical centromeres. In another case, the rings were similar to WDLPS-ALP rings, but a large marker contained a chromosome 5 centromere and amplified alpha-satellite sequences from chromosome 8. ALP-WDLPS is the first example of a tumor class for which the presence of stable analphoid chromosomes is a constant and specific abnormality. Formation of newly derived centromeres, so-called neocentromeres, could be an original and effective way to maintain a selective advantage in neoplastic cells by conferring stability to the supernumerary chromosomes of ALP-WDLPS. The activation of normally non-centromeric sequences might be obtained by an epigenetic mechanism due to the peculiar chromatin conformation of these highly complex chromosomes.

[Clear cell soft tissue sarcoma. Clinical, histopathological and prognostic study of 36 cases]

Thirty six cases of clear cell sarcoma of soft tissue are reported. The median age was 44 years (5 to 80 years). The principal sites were the foot (11 cases), the hand and wrist (7 cases) and the knee (6 cases). The architecture was fascicular with lobular arrangement of cells delimited by delicate fibrous septa intimately bound to tendons or aponeuroses. Tumoral cells were round or fusiform with abundant clear cytoplasm sometimes epithelioid with round nuclei and prominent nucleoli. The mitotic rate was evaluated to 9/10 HPF. S100 protein was expressed in 33/36 cases and HMB45 marked 29/31 cases, without expression of cytokeratin. Three-year and 5-year survival rate were respectively 72% and 62%. Prognosis factors for global survival were efficiency of initial treatment with distal location and necrosis and FNCLCC grade. The distinction of clear cell sarcoma from metastatic melanoma is important because of the difference of prognosis.

Lipomatous hemangiopericytoma: a fat-containing variant of solitary fibrous tumor? Clinicopathologic, immunohistochemical, and ultrastructural analysis of a series in favor of a unifying concept

The dinicopathologic, immunohistochemical and ultrastructural features of 13 lipomatous hemangiopericytomas are presented. There were 6 male and 7 female patients whose ages at diagnosis ranged from 27 to 75 years (median 48) all presenting with a mass of variable duration. The tumor sizes ranged from 1.7 cm to 19 cm (median 5.5 cm). The locations included the orbit (1), neck (1), mediastinum (1), epicardium (1), retroperitoneum (3), right iliac fossa (1), and upper (1) and lower (4) extremity. Histologically, the lesions were composed of a varying admixture of spindle-shaped to round cells, variably collagenous stroma, adipose tissue, and branched, often thick-walled, hemangiopericytoma-like vessels. For 11 tumors, the mitotic activity ranged from 1 to 3 mitoses per 10 high-power fields (HPF). One tumor which contained hypercellular areas showed 13 mitoses per 10 HPF, and another hypercellular lesion showed up to 43 mitoses per 10 HPF, abnormal mitoses, and necrosis. Immunohistochemically, tumor cells were invariably positive for vimentin and CD99, and mostly for CD34 but negative for desmin, keratin, CD31, CD117 (c-kit), and inhibin. About half of the tumors showed reactivity for bcl-2. Occasionally, focal reactivity was also observed for smooth muscle actin, muscle-specific actin, S100 protein, and epithelial membrane antigen. Ultrastructural examination of seven cases showed features in keeping with fibroblastic, myofibroblastic, or pericytic differentiation. Treatment consisted of simple tumorectomy in 10 cases and wide excision in 3. Follow-up information on 10 patients (range: 6 to 77 months; median: 18 months) showed no recurrence. Lipomatous hemangiopericytoma which share the clinical, pathologic, immunohistochemical, and ultrastructural features of solitary fibrous tumor (SFT) is likely to represent, in most cases, a fat-containing variant of SFT.

Orbital and extraorbital giant cell angiofibroma: a giant cell-rich variant of solitary fibrous tumor? Clinicopathologic and immunohistochemical analysis of a series in favor of a unifying concept

The clinicopathologic and immunohistochemical features of one orbital and nine extraorbital soft tissue lesions, the morphology of which overlaps with giant cell angiofibroma and solitary fibrous tumor, are presented. There were 3 male and 7 female patients. Age at diagnosis ranged from 18 to 81 years (median: 45 yrs). Development of a mass was the main presenting symptom. For two patients, the lesion had been evident for several years before excision. Extraorbital tumors were located in the head and neck area (3), back (3), retroperitoneum (1), hip (1), and vulva (1). Tumor size ranged from 1.3 cm to 11 cm (median: 4.5 cm). The lesions presented grossly as well-demarcated, unencapsulated soft tissue masses. Histologically, they were characterized by the presence of alternating cellular and sclerosing areas, keloidal collagen deposition, round- to staghorn-shaped, thick-walled vessels and multinucleated giant stromal cells often lining pseudovascular spaces. Cellular areas were composed of non-atypical spindle to round cells set in a variably collagenous background. Mitotic activity ranged from 1 to 3 mitoses/10 high-power fields. Immunohistochemical studies showed positive staining of the spindle/round cells and multinucleated stromal cells invariably for vimentin, CD34, CD99, and mostly for bcl-2 but negative for muscle specific actin, desmin, CD31, CD117 (c-kit), and inhibin. Occasionally, focal reactivity was observed for smooth muscle actin, S-100 protein, epithelial membrane antigen, and keratin. Treatment consisted of simple tumorectomy in eight patients and wide excision in two. Follow-up information for eight patients (range: 7-32 mos; median: 14 mos), including four with microscopically positive surgical margins, showed no recurrence. These lesions share the clinical, pathologic, and immunohistochemical features of giant cell angiofibroma and solitary fibrous tumor, supporting the view that these tumors are closely related. In addition, it shows that giant cell angiofibroma occurs equally in both sexes and has a wider distribution than initially thought, developing even more often in extraorbital locations than in the orbit.

Sarcoma after radiation therapy: retrospective multiinstitutional study of 80 histologically confirmed cases. Radiation Therapist and Pathologist Groups of the Fédération Nationale des Centres de Lutte Contre le Cancer

PURPOSE

To evaluate the best strategy for treatment of sarcoma that occurs after radiation therapy.

MATERIALS AND METHODS

Records were retrospectively reviewed for 80 patients with a confirmed histologic diagnosis of sarcoma that occurred after radiation therapy performed during 1975-1995. The patients were treated for breast cancer (n = 33, 42%), non-Hodgkin lymphoma (n = 9, 11%), cervical cancer (n = 9, 11%), benign lesions (n = 4, 5%), or other tumors (n = 25, 31%). Sarcoma occurred after a mean latency of 12 years (range, 3-64 years), with most (70%) developing in the soft tissue. Treatment included surgery (28 patients), surgery and chemotherapy (18 patients), chemotherapy only (15 patients), and radiation therapy (14 patients).

RESULTS

By the end of the study, 51 patients were dead, including 46 due to sarcoma. Median survival was 23 months. Overall survival rates at 2 and 5 years, respectively, were 69% and 39% for patients treated with surgery, 10% and 0% for those treated with chemotherapy, and 52% and 35% for those treated with surgery and chemotherapy (P =.001). The 2- and 5-year rates for survival without recurrence were 54% and 32%, respectively.

CONCLUSION

The results confirm the beneficial effect of surgery. Further study is needed to explore the roles of combined treatments.

Metastasizing fibrous histiocytoma of the skin: a clinicopathologic and immunohistochemical analysis of three cases

The clinicopathologic and immunohistochemical features of three metastasizing fibrous histiocytomas of the skin are presented. The first patient had a 1.3-cm nodule in the right thigh, with right inguinal lymph node metastases 19 years later. The second patient, who had a 3-cm nodule excised from his left thigh and inguinal lymph node metastasis after 4 months, had a favorable outcome 14 years after local radiotherapy and chemotherapy. The third had a 2-cm nodule in his neck, which recurred 16 months later. Four months later, cervical lymph node metastases were found. The patient was alive and well 26 months after initial surgery. All three primary skin tumors involved the dermis and subcutis, appeared well-delineated but nonencapsulated, were associated with some degree of epidermal hyperplasia, and showed features of aneurysmal/atypical or cellular fibrous histiocytoma. The number of mitoses ranged from 6 to 11 per 10 high-power fields. Recurrences and metastases showed morphologic features similar to primary lesions. Tumor cells were positive, at least focally, for CD 68, Ki-M1p, and Factor XIIIa, and occasionally for smooth muscle actin. Desmin, CD 34, S-100 protein, and cytokeratin stainings were negative. Primary neoplasms, recurrences, and metastases showed a Mib-1 labeling index of 10% or less. Cellular, aneurysmal, and atypical (pseudosarcomatous) fibrous histiocytomas of the skin can metastasize, yet they often show a protracted clinical course. Risk factors for metastatic dissemination include large size, high cellularity, aneurysmal changes, marked cellular pleomorphism, high mitotic activity, tumor necrosis, and repeated local recurrences.