Differential expression of neural-cadherin in pulmonary epithelial tumours.

AIMS: Neural (N)-cadherin belongs to a group of transmembrane molecules with a crucial role in tissue morphogenesis and maintenance of an epithelioid phenotype and increased N-cadherin expression is implicated in tumour progression and dedifferentiation. The aim was to determine whether evaluation of N-cadherin in pulmonary tumours might assist in identifying lesions with more aggressive potential. METHODS AND RESULTS: One hundred and fifty-five pulmonary lesions were analysed for N-cadherin expression using immunohistochemistry, including neuroendocrine hyperplasia (n = 3), typical carcinoid (n = 59), atypical carcinoid (n = 12), small cell lung carcinoma (n = 11), large cell neuroendocrine carcinoma (n = 12), adenocarcinoma (n = 35) and squamous cell carcinoma (n = 23). Lymph node status was correlated with immunohistochemical expression. N-cadherin expression was demonstrated in all cases of neuroendocrine hyperplasia, 96% of typical carcinoids, 83% of atypical carcinoids, 63% of the small cell lung carcinomas and 32% of large cell neuroendocrine carcinomas. Over 90% of the adenocarcinomas and 100% of the squamous cell carcinomas were negative. Increased N-cadherin expression in typical carcinoids was associated with negative lymph node status (P < 0.001). DISCUSSION: N-cadherin is differentially expressed in pulmonary tumours and is predominantly observed in neuroendocrine lung lesions with high expression in typical and atypical pulmonary carcinoids. The level of expression of N-cadherin between types of lung tumours does not appear to indicate malignant potential or aggressive behaviour.

Tumors in dogs exposed to experimental intraoperative radiotherapy.

PURPOSE: The frequency of radiation-induced neoplasms was determined in dogs enrolled in the National Cancer Institute canine trials of intraoperative radiotherapy (IORT). METHODS AND MATERIALS: Twelve protocols assessing normal tissue response to IORT involved 238 dogs in a 15-year trial. Eighty-one dogs were followed for > 24 months postoperatively and were assessed for tumor development; 59 of these animals received IORT. RESULTS: Twelve tumors occurred in the 59 dogs receiving IORT. Nine were in the IORT portals and were considered to be radiation induced. No tumors occurred in 13 sham animals or in 9 animals treated with external beam radiotherapy alone. The frequency of radiation-induced malignancies in dogs receiving IORT was 15%, and was 25% in animals receiving > or = 25 Gy IORT. Frequency of all tumors, including spontaneous lesions, was 20%. CONCLUSIONS: Intraoperative radiotherapy contributed to a high frequency of sarcoma induction in these dogs. Unknown to date in humans involved in clinical trials of IORT, this potential complication should be looked for as long-term survivors are followed.

Malignant fibrous histiocytoma associated with hyperlipoproteinemia.

A unique case of malignant fibrous histiocytoma arising within the thigh of a patient with Type II A (hypercholesterolemic) hyperlipoproteinemia is described. The tumor, which appeared grossly as a benign tuberous xanthoma, demonstrated pleomorphic spindled and multinucleated cells focally in the distinct storiform pattern of a malignant fibrous histiocytoma and areas composed of bland xanthoma cells associated with cholesterol deposits. Foci of xanthoma cells with mildly atypical nuclei admixed with highly pleomorphic cells were also noted. These unusual histologic features--as well as the uniform staining of all the tumor cells with anti-alpha-1-antichymotrypsin and the absence of anti-alpha-1-antitrypsin and of anti-lysozyme staining--support the conclusion that all elements of this malignant tumor were derived from a common mesenchymal precursor. The exaggerated histiocytic capability of the tumor cells in the form of xanthomatous change was probably in response to the hyperlipoproteinemic microenvironment.

Epithelioid variant of malignant peripheral nerve sheath tumor (malignant epithelioid schwannoma).

Twenty-six cases of malignant peripheral nerve sheath tumor with a predominant epithelioid pattern were studied to determine the range of its histologic patterns, immunophenotype, and biologic behavior. The tumor presented as an asymptomatic mass either in superficial (16 cases) or in deep soft tissue (10 cases) of the extremity. Characteristically, those in deep soft tissue were composed of vague nodules of varying cellularity made up of cords or strands of rounded epithelioid cells with prominent nucleoli. Those in superficial soft tissue were uninodular masses composed of tight clusters of cells showing cell-to-cell molding but possessing the same prominence of nuclei and mitotic activity as those in deep soft tissue. Several were associated with a preexisting benign nerve sheath tumor. A number of cases deviated from the above description, including cases that resembled a clear cell carcinoma, a malignant rhabdoid tumor, and a pleomorphic sarcoma. The majority of cases (80%) strongly expressed S-100 protein and neuron-specific enolase, but all lacked a melanoma-associated antigen (as defined by HMB-45) and cytokeratin. Stains for type IV collagen defined linear immunoreactivity around single cells and groups of cells. This pattern did not differ substantially from that of melanomas and therefore did not serve as a reliable discriminant. Follow-up information indicated a more favorable course for those in superficial soft tissue compared with those in deep sites. Two of 16 patients in the former group developed metastatic disease compared with three of 10 in the latter group. Tumors in superficial soft tissue may be eminently treatable and curable, depending on size.

Angiomyofibroblastomalike tumor of the male genital tract: analysis of 11 cases with comparison to female angiomyofibroblastoma and spindle cell lipoma.

The clinicopathologic features and immunoprofile of 11 cases of an uncharacterized male genital tract tumor with features of vulvovaginal angiomyofibroblastoma (AMF) and spindle cell lipoma (male AMF-like tumor) are described. The lesions presented as a mass involving the scrotum (six cases) or inguinal region (five cases) in males ranging in age from 39 to 88 years (median 57). The tumors were superficially located and well-marginated and ranged in size from 2.5 to 14 cm (approximate mean 7 cm). Microscopically, they were composed of tapered spindled cells proliferating between numerous small to medium-sized vessels. Epithelioid appearing stromal cells were a focal finding in four cases. Mitotic activity was minimal with no abnormal mitotic figures identified. Mild nuclear atypia was identified in two cases. The tumors possessed an acid mucopolysaccharide-rich, finely collagenous stroma. A small quantity of intralesional fat was present in six cases. Tumor cells exhibited immunoreactivity for vimentin (seven of seven cases), progesterone receptor protein (five of seven cases), CD34 (four of eight cases), estrogen receptor protein (three of seven cases), desmin (three of eight cases), muscle-specific actin (three of eight cases), and smooth-muscle actin (two of eight cases) but not for S-100 protein. One of seven patients with follow-up after simple excision had recurrent/persistent disease. The male AMF-like tumor is a soft-tissue neoplasm of the male genital tract that shares clinicopathologic features and a proposed perivascular stem cell derivation with both the female angiomyofibroblastoma and spindle cell lipoma.

A clinicopathologic study of 45 pediatric soft tissue tumors with an admixture of adipose tissue and fibroblastic elements, and a proposal for classification as lipofibromatosis.

The tumor described here as lipofibromatosis is a rare pediatric neoplasm that has been variously interpreted as a type of infantile or juvenile fibromatosis, a variant of fibrous hamartoma of infancy, and a fibrosing lipoblastoma. This report details the clinicopathologic features associated with 45 cases of this soft tissue entity. The study group consisted of 32 males, 12 females, and one person of unstated gender. The patients presented with a soft tissue mass (range, 1-7 cm) involving the hand (n = 18), arm (n = 8), leg (n = 7), foot (n = 6), trunk (n = 5), or head (n = 1). Eight tumors were evident at birth. The individuals ranged in age from 11 days to 12 years (median age, 1 yr) at the time of initial biopsy or resection. Microscopic examination revealed abundant adipose tissue with a spindled fibroblastic element that chiefly involved the septa of fat and skeletal muscle. The process generally did not cause extensive architectural effacement of fat as is common with conventional fibromatoses, and it did not have a primitive nodular fibromyxoid component as is characteristic of fibrous hamartoma of infancy. The fibroblastic element exhibited focal fascicular growth and typically had limited mitotic activity (< or = 1 mitosis/ 10 high-power fields) and cytologic atypia. Oftentimes, small collections of univacuolated cells were present at the interface between some of the fibroblastic fascicles and the mature adipocytes. The tumors entrapped vessels (n = 45), nerves (n = 44), skin adnexa (n = 16), and skeletal muscle (n = 18). Focal immunoreactivity was present in some tumors for CD99, CD34, alpha-smooth muscle actin, BCL-2, and less frequently, S-100 protein, muscle actin (HUC 1-1), and EMA. However, no reactivity was detected for desmin (D33 and D-ER- 1 clones), keratins, or CD57. Follow-up data were available for 25 individuals (median follow-up period, 6 yrs 7 mos) with regrowth of the tumor or persistent disease documented in 17 (72%). The following events were more common in the group with recurrent or persistent disease: congenital onset, male sex, hand and foot location, incomplete excision, and mitotic activity in the fibroblastic element. Although it is likely this tumor comprises part of the spectrum of what has been referred to in the literature as infantile/juvenile fibromatosis, its clinicopathologic features and, in particular, its distinctive tendency to contain fat as an integral component, warrant separate classification as a "lipofibromatosis."

Occult papillary carcinoma of the thyroid with pulmonary metastases.

This case report describes an occult papillary adenocarcinoma of the thyroid with pulmonary metastases, discovered at autopsy. Since papillary adenocarcinoma of the thyroid usually invades adjacent structures and cervical lymph nodes in a predictable fashion, the finding of distant hematogenous spread, when the tumor is confined to the thyroid gland, is unusual, as is illustrated by a review of the literature. The patient's history included a poorly differentiated squamous cell carcinoma of the lung, which had been resected 15 years prior to death and had been followed by super-voltage radiation. The possible effects of super-voltage radiation on the pathogenesis and behavior of thyroid cancer are discussed.

The "neurothekeoma": immunohistochemical analysis distinguishes the true nerve sheath myxoma from its mimics.

In contrast with the myxoid variant of neurothekeoma (nerve sheath myxoma), evidence of neurosustentacular (NS) differentiation in the so-called cellular and mixed (intermediate) variants of neurothekeoma remains controversial. In this study, we selected 22 tumors coded as neurothekeoma or nerve sheath myxoma from the Soft Tissue Registry of the AFIP. Each tumor was histologically subtyped as either a myxoid/hypocellular neurothekeoma (MN) (N = 11) or as a "cellular" or "mixed" (intermediate) neurothekeoma variant (C&MV) (n = 11) and analyzed immunohistochemically. The MNs were composed of small, cytologically bland cells arranged in a loose cellular network or in files within highly myxomatous nodules delineated by dense collagen. The tumors showed clear-cut evidence of NS differentiation by exhibiting consistent immunoreactivity for S-100 protein (11 of 11 cases) and low-affinity nerve growth factor receptor, p75(NGFR), (NGFR) (10 of 10), and variable reactivity for glial fibrillary acidic protein (GFAP) (10 of 11) and CD57 (Leu-7) (5 of 9). They also showed pericellular collagen type IV (CIV) expression (9 of 9), scattered intralesional CD34-positive spindled cells (10 of 10), epithelial membrane antigen (EMA)-positive spindled cells located within the adjacent dense collagen (8 of 11), and immunoreactivity for alpha-smooth muscle actin (SMA) (3 of 10) and calponin (4 of 9). In 4 cases, scattered intralesional neuraxons were detected by the Bodian histochemical method or immunohistochemically with anti-neurofilament protein. The tumors had a male-to-female ratio of 6:5, a peak incidence in the 4th decade of life, and an anatomic distribution that included the upper and lower limbs and back. The C&MVs included 9 "mixed" and 2 "cellular" variants. C&MVs differed histologically from MNs by their higher cellularity and presence of larger spindled or epithelioid cells with vesicular nuclei. Immunohistochemically, the tumor cells expressed CIV (9 of 10), calponin (7 of 9), SMA (5 of 10), Leu-7 (1 of 7), S-100 protein (1 of 11), but not NGFR, GFAP, or CD34. EMA-positive spindled cells surrounded tumor fascicles in 1 case. Intralesional neuraxons were not identified. Clinically, these tumors differed from the MNs by exhibiting a male-to-female ratio of 4:7, a peak incidence in the 2nd decade, and an upper body distribution. Our results indicate that the MN shows NS differentiation and is the bona fide nerve sheath tumor, whereas the C&MVs fail to show convincing evidence of NS differentiation and probably warrant a separate classification.

Superficial acral fibromyxoma: a clinicopathologic and immunohistochemical analysis of 37 cases of a distinctive soft tissue tumor with a predilection for the fingers and toes.

This report describes the clinicopathologic features and immunohistochemical findings identified in 37 cases of a distinctive soft tissue tumor that has a predilection for the hands and feet. The study group included 25 male and 12 female subjects ranging in age from 14 to 72 (mean, 43; median, 46) years. The patients presented with solitary masses 0.6 to 5.0 cm (mean, 1.75 cm) that were present from 3 months to 30 years (median duration, approximately 3 years) before surgical intervention and involved the toes (n = 20), fingers (n = 13), and palm (n = 4). Twenty of the cases were documented to involve the nail region. Histologically, the tumors were typically located in the dermis or subcutis and composed of spindled and stellate-shaped cells with random, loose storiform, and fascicular growth patterns. The lesional cells were embedded in myxoid or collagenous matrix, often with mildly to moderately accentuated vasculature and increased numbers of mast cells. There was generally slight to mild nuclear atypia; only 3 cases had more substantial atypia. Mitotic figures were infrequent. Occasional multinucleated stromal cells were noted in 19 cases. The process showed immunoreactivity for CD34 (21 of 23 cases), epithelial membrane antigen (18 of 25 cases), and CD99 (11 of 13 cases). No immunoreactivity was detected for actins, desmin, keratins, or HMB-45, and only 1 of 23 tumors had weak reactivity for S100 protein. The surgical specimens consisted of biopsy or partial resection specimens (n = 4), local excisions (n = 29), and amputated or partially amputated digits (n = 4). Detailed follow-up, available for 18 patients (mean follow-up interval, 10.1 years), revealed 1 recurrence after local excision and 2 instances of persistent or progressive disease after partial excision. A differential diagnosis of fibrous histiocytoma, dermatofibrosarcoma protuberans, acquired (digital) fibrokeratoma, sclerosing perineurioma, cutaneous myxoma (superficial angiomyxoma), and acral myxoinflammatory fibroblastic sarcoma is discussed.

Angiomyofibroblastoma of the female genital tract: analysis of 17 cases including a lipomatous variant.

The clinicopathological and immunohistochemical profile of 17 cases of angiomyofibroblastoma (AMF) arising in the genital tract of females is reported. The lesions usually presented as painless masses and were located in the superficial vulvar region (15 cases), canal of Nuck (one case), and perineum (one case) in women ranging in age from 38 to 60 years (median, 46 years). The tumors were well delineated and ranged in size from 2 to 8 cm in greatest dimension. Microscopically, they were composed of spindled and epithelioid mesenchymal cells arranged in cords and nests preferentially arrayed around numerous small to medium-sized vessels. Mitotic activity ranged from 0 to 7 mitoses per 50 high-power fields (HPF) with no abnormal mitotic figures. Minimal nuclear atypia was appreciated. Intralesional fat was present in 12 cases and in two of these cases constituted most of the tumor (lipomatous variant of AMF). Tumor cells expressed vimentin (five of five cases), estrogen receptor protein (six of six cases), progesterone receptor protein (five of six cases), desmin (six of eight cases), CD34 (one of six cases), and smooth muscle actin (one of seven cases). None of the eight women with follow-up of up to 25 years (mean, 7.8 years) after simple excision developed a recurrence. This study confirms the benign nature of AMF, broadens its morphological spectrum to include a lipomatous variant, and proposes an origin from a perivascular stem cell that is capable of myofibroblastic and fatty differentiation.

Superficial cervicovaginal myofibroblastoma: fourteen cases of a distinctive mesenchymal tumor arising from the specialized subepithelial stroma of the lower female genital tract.

The clinicopathologic features and immunohistochemical profiles of 14 cases of a distinctive mesenchymal tumor that arises in the superficial lamina propria of the cervix and vagina and is histologically distinguishable from mesodermal (fibroepithelial) stromal polyp, including the cellular (pseudosarcomatous) variant, angiomyofibroblastoma, aggressive angiomyxoma, and other well-recognized lesions that occur in this location, are described. The lesions presented as a polypoid (n = 10) or nodular (n = 4) mass in the vagina (n = 12) or cervix (n = 2) of women ranging in age from 40 to 74 years (median, 58 years). The tumors were subepithelial in location, were well circumscribed, and ranged in size from 1 to 6.5 cm. (mean, 2.7 cm). Microscopically, the process was moderately to highly cellular and composed of relatively bland spindled and stellate-shaped mesenchymal cells embedded in a finely collagenous stroma that was punctuated by myxoid and edematous foci in 9 cases. The lesions characteristically had a multipatterned architecture with tumor cells focally assuming a lacelike/sievelike growth pattern in the more stroma-rich areas of the tumor and a vague fascicular growth pattern in the more cellular foci. Mitotic activity was minimal, and no atypical mitotic figures were identified. The tumors were immunoreactive (in decreasing order of relative strength) for vimentin (5 of 5 cases), estrogen (10 of 10 cases), and progesterone (10 of 10 cases) receptors, desmin (13 of 13 cases), CD34 (11 of 13 cases), alpha-smooth muscle actin (5 of 11 cases), and muscle-specific actin (2 of 8 cases). The desmin and CD34 antibodies highlighted the interconnecting, dendritic processes associated with many of the tumor cells. No immunoreactivity was detected for S100 protein, epithelial membrane antigen, or keratins. Follow-up data for 11 patients (range, 1 to 20 years; median, 4 years) showed no recurrence or metastasis after local excision. The term "superficial cervicovaginal myofibroblastoma" is proposed because it reflects the distinguishing features of this benign, relatively site-specific mesenchymal tumor. The process probably arises as a neoplastic proliferation of hormonally responsive mesenchymal cells native to the unique subepithelial stromal layer normally found through the endocervix and vulva of adult women.

An intra-abdominal small round cell neoplasm with features of primitive neuroectodermal and desmoplastic round cell tumor and a EWS/FLI-1 fusion transcript.

We report an intra-abdominal round cell tumor in a young man which exhibited the light and electron microscopic appearance of a peripheral primitive neuroectodermal tumor (PNET), in addition to the clinical and topographic characteristics, desmoplasia and a complex immunophenotypic profile of the intra-abdominal desmoplastic round cell tumor (DSRCT). Reverse transcription polymerase chain reaction revealed a EWS/FLI-1 fusion transcript as in PNET/Ewing's sarcoma, instead of the EWS/WT1 transcript of DSRCT. The tumor was also strongly positive for the mic2 protein. This is a unique case of a hybrid tumor arising in the peritoneal cavity of a young male. The existence of such a hybrid tumor in this location suggests that DSRCT and PNET may be related and possibly share a common histogenesis.

Follicular dendritic cell tumor presenting in the lung: a case report.

An example of extranodal follicular dendritic cell sarcoma (FDCS) presenting in the lung, a heretofore unreported site, is described. Macroscopically, a 9.5-cm, tan-white, dominant mass and multiple smaller parenchymal and pleural nodules were identified. Microscopically, the tumor was composed of spindled cells with uniform cytologic features arranged in short, intersecting fascicles and intermixed small lymphocytes and plasma cells. One of 4 peribronchial and hilar lymph nodes evaluated microscopically was focally involved by the process. Immunohistochemically, the neoplastic spindled cells expressed complement receptors CD21 and CD35 and low-affinity nerve growth factor receptor but did not express keratin (AE1/AE3 and CAM5.2), CD45 (leukocyte common antigen), CD20 (L26), S-100 protein, muscle-specific actin, or gp100 protein (HMB45). Ultrastructurally, the tumor cells have complex interdigitating cell surface processes and desmosomes. Epstein-Barr virus (EBV) was not detected in the tumor cells by in situ hybridization for EBV-encoded RNA or by polymerase chain reaction for viral DNA. FDCS should be considered in the differential diagnosis of any spindled-cell tumor with interspersed chronic inflammatory cells occurring in the lung. An immunohistochemical panel, including anti-CD21 and -CD35, can assist in its diagnosis, especially with small bronchial biopsy specimens. 2001 by W.B. Saunders Company.

Colposcopy in pregnancy: directed brush cytology compared with cervical biopsy.

OBJECTIVE: To evaluate colposcopically directed brush cytology as a substitute for directed biopsy of acetowhite lesions identified during pregnancy. METHODS: Pregnant patients eligible for the study were referred for colposcopic evaluation for either newly diagnosed abnormal cervical cytology or follow-up of a previously diagnosed squamous intraepithelial lesion (SIL). All patients with acetowhite lesions underwent colposcopically directed brush cytology followed by directed biopsy. RESULTS: Of 81 pregnant patients referred, 50 paired samples of colposcopically directed brush cytology and directed biopsies were evaluated from 49 patients. One patient was sampled in the first and third trimesters and one patient's brush cytology was unsatisfactory for interpretation because of clumping artifact, leaving 49 brush-biopsy pairs that were satisfactory for examination. One patient in the study group had an intrauterine fetal death of uncertain cause, remote from the time of biopsy. Compared with the corresponding biopsy, the directed brush caused significantly less blood loss (P < .001). For all diagnostic categories, directed cytology demonstrated a good degree of correlation with biopsy (kappa = 0.73). The brush technique correctly identified 12 of 14 cases (86%) of biopsy-proved cervical intraepithelial neoplasia II-III as high-grade SIL. If one considers "atypical squamous cells, favor human papillomavirus effect" as a true positive, brush sensitivity was 88 +/- 9% and specificity was 74 +/- 12%, with an accuracy of 80%. CONCLUSION: In the absence of lesions suspicious for carcinoma, colposcopically directed brush cytology is a safe substitute for directed biopsy in pregnant patients.

Transitional cell carcinoma of the kidney with tumor thrombus into the vena cava.

Transitional cell carcinoma of the upper urinary tract with inferior vena cava tumor thrombus is an unusual entity. We report the 16th such case and review the previous cases in the world literature. Preoperative diagnosis was correct in only 5 of the cases. This type of condition can be easily presumed to be renal cell carcinoma. Fifteen of the cases were managed with radical nephrectomy; 8 patients were managed with partial or complete resection of the vena cava due to adherence of the tumor thrombus to the vessel wall. Overall outcome was poor, with short postoperative survival. Correct preoperative diagnosis, although difficult, could allow more complete preoperative planning or appropriate nonoperative management.

Solitary fibrous tumor of the prostate a report of 2 cases and review of the literature.

We report 2 cases of solitary fibrous tumor of the prostate. Histologically, both tumors demonstrated a multipatterned architecture with varying degrees of collagenization and hemangiopericytoma-like foci, and both were composed of CD34-immunopositive spindled cells that insinuated themselves between strips of collagen. The tumor in case 1 was well circumscribed and showed minimal mitotic activity or pleomorphism, whereas the tumor in case 2 was more cellular, less collagenous, had a more diffuse growth pattern, and exhibited cytologic atypia and high mitotic activity. Prostatic solitary fibrous tumor must be distinguished from other spindle cell tumors reported to occur in the prostate. To our knowledge, these cases represent only the fifth and sixth reported cases of prostatic solitary fibrous tumor.

Dermatofibrosarcoma protuberans.

Dermatofibrosarcoma protuberans is an intermediate-grade sarcoma that arises in the dermis of the trunk, proximal extremities, and less commonly, in the head and neck area of adults. Dermatofibrosarcoma protuberans has a deceptively innocuous early clinical appearance and generally exhibits an indolent course for years before entering a rapid growth phase. Its locally invasive behavior results in early recurrence if prompt, wide excision is not performed. Dermatofibrosarcoma protuberans rarely metastasizes through the bloodstream or, less often, to locoregional lymph nodes after multiple local recurrences. Fibrosarcomatous areas within the tumor result in a more aggressive course. Although wide excision is the mainstay of therapy, recent trials using the Mohs' surgical approach suggest that this technique may have a role in the future treatment of this tumor.

Postradiation soft tissue sarcomas. An analysis of 53 cases.

The clinicopathologic features of 53 cases of postradiation soft tissue sarcoma (PRS) were correlated with the physical characteristics of the administered radiation. All but three patients received radiation for malignant processes. Of the secondary sarcomas, malignant fibrous histiocytoma (MFH) accounted for 36 cases (68%), followed by seven extraskeletal osteosarcomas (13%), six fibrosarcomas (11%), two malignant Schwannomas (4%), one extraskeletal chondrosarcoma, and one angiosarcoma. The sex incidence, age of the patient at time of diagnosis, and location of the PRS correlated only with the clinical characteristics of the initial treated condition. The latency period (mean 10 years) showed an indefinite relationship to patient survival but no definite relationship to the patient's age at the time of the initial radiation. There was no difference between patients treated with megavoltage radiation (39 patients) and with orthovoltage radiation (seven patients) in the type of sarcoma, location, or survival, although the orthovoltage group received a lower mean radiation dose (3880 rads) than the megavoltage group (4446 rads). Megavoltage radiation, however, produced deeper tissue radiation changes and was associated with a shorter latency period. Most PRS were poorly differentiated, produced abundant collagen, and had a dismal prognosis.