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Carcinoid tumors are slow growing, low-grade malignant neoplasms that are believed to originate from neuroendocrine cells, usually in the gastrointestinal mucosa. Metastasis of carcinoid tumor to the orbit is a rare occurrence. When metastasis does occur, the choroid is the most common ocular structure involved. We report two cases of unique involvement of extraocular muscles.
Although a number of studies have demonstrated proliferation of nonneoplastic astrocytes in experimental animal models, the proliferative potential of human astrocytes has not been well defined. Using double-label immunohistochemistry, we identified proliferating cells with the proliferation marker MIB-1 and astrocytes with glial fibrillary acidic protein staining in human biopsy and autopsy tissue. MIB-1 labeling of astrocytes was monitored in a variety of conditions containing significant numbers of reactive astrocytes, including infections, arteriovenous malformations, demyelinating lesions, metastatic tumors, and long-standing gliosis. Twenty-nine of a total of 54 cases showed no evidence of astrocyte-specific MIB-1 labeling despite prominent reactive changes. An average proliferation rate of 0.9% was present in the remaining 25 cases. Labeling indices were highest in infectious conditions and acute demyelinating lesions. We also examined astrocyte proliferation in 5 cases of progressive multifocal leukoencephalopathy. Astrocytic labeling indices were notably elevated in these cases, with an average labeling index of 5.8%. We conclude that low, but appreciable, astrocytic proliferation may occur in nonneoplastic human astrocytes. These findings have implications for astrocyte function in the normal and disease states and for the diagnostic distinction between reactive lesions and low-grade astrocytic neoplasms.
Current theory suggests that transitional cell carcinoma (TCC) occurs as either of 2 disease processes, each of which has a distinct cytologic appearance and clinical course: low-grade and high-grade TCC. Urinary cytology has become a mainstay technique for monitoring disease recurrence in patients with TCC. Most cases of high-grade TCC can be diagnosed accurately in urinary cytology specimens. However, the cytologic diagnosis of low-grade TCC is difficult; these tumors exhibit subtle cytomorphologic alterations that are difficult to distinguish from benign or reactive processes. The cytologic criteria most useful for diagnosing low-grade TCC in urinary cytology specimens are reviewed. Additionally, the discussion includes some of the new ancillary tests that are emerging as possible diagnostic aids for the detection of low-grade urothelial neoplasms.
Kaposi sarcoma (KS) is a low-grade vascular neoplasm associated with human herpesvirus-8 (HHV-8) infection. Clinically, lesions commence as blue-red macules that may develop into plaques and eventually into nodules. The histologic appearance spans a broad spectrum and varies with the stage of the lesion. At each stage, KS has significant morphologic overlap with other vasoproliferative lesions. Recently, we encountered 6 KS tumors that histologically mimicked pyogenic granuloma (PG), a common benign vascular tumor of the skin that usually does not figure in the histologic differential diagnosis of KS. We stained 6 PG-like KS and 28 PGs with a mouse monoclonal antibody (13B10) against HHV-8 latent nuclear antigen-1 (LNA-1) to determine the utility of immunoperoxidase staining in distinguishing KS from PG. All 6 PG-like KS demonstrated nuclear staining for HHV-8 LNA-1. No staining was identified in any of the 28 PGs. Histologic criteria often used to differentiate between these two entities were not helpful in our cases. The only distinguishing feature was the presence or absence of HHV-8 LNA-1 staining. The presence of HHV-8 LNA-1 nuclear staining seems to be a specific marker for KS when comparing PGs and PG-like KS. Immunoperoxidase staining for HHV-8 LNA-1 is a useful diagnostic tool in this setting.
In reviewing all proliferative serous tumors of the ovary seen at Barnes Hospital from 1950 to 1974, we quantitated histologic characteristics and defined criteria for diagnosis in 55 borderline tumors, 13 well-differentiated cystadenocarcinomas, and 15 cystadenomas with unusual proliferative areas. This last type with focal proliferation behaved in a benign fashion and should be considered a variant of a simple cystadenoma. Stromal invasion was the only histologic feature which consistently distinguished carcinomas from the borderline tumors. The presence in some borderline tumors of severe cellular atypia, marked epithelial disorganization, frequent mitoses, and cribriform glands in the stroma neither signified carcinoma nor indicated poor prognosis. No patient with a Stage I borderline lesion died of tumor. Although the mortality of patients with Stage IIb or Stage III borderline tumors is high, tumor-related deaths rarely occurred before 5 years, and three patients lived more than 10 years. Borderline serous tumors are low-grade malignant neoplasms which differ from overt carcinomas in the excellent prognosis of Stage I lesions and in long survival even with widespread abdominal disease.
Twelve cases are reported of primary epithelioid hemangioendothelioma of the anterior mediastinum. Patient ages ranged from 19 to 62 years (mean, 49.4); three were women and nine were men. Seven patients presented with symptoms due to compression of surrounding structures; the remainder were asymptomatic and the lesions were discovered on routine chest x-ray films. The tumors measured from 4.5 to 13.5 cm in greatest diameter; they were encapsulated and well-circumscribed in seven cases and locally infiltrative in five. Histologically, a spectrum of features was observed ranging from those classically described for low-grade epithelioid hemangioendothelioma at other locations--including cells with abundant eosinophilic cytoplasm showing prominent vacuolization and intracellular lumen formation, few mitotic figures, and myxoid changes in the stroma--to more pronounced cytologic atypia, increased mitotic activity, and areas of necrosis. Metaplastic bone formation and osteoclast-type giant cells were observed in five cases, and four tumors displayed focally a prominent intravascular papillary endothelial component. Immunohistochemical studies showed positive staining of the neoplastic cells with factor VIII-related antigen and vimentin and focal staining in most cases with Ulex europaeus lectin. Stains for broad-spectrum keratin, CAM-5.2, S-100 protein, CD34, actin, and desmin were negative. Electron microscopic examination in three cases showed features distinctive for epithelioid vascular endothelial cells, including abundant cytoplasmic intermediate filaments, basal lamina material, marked pinocytotic activity, and primitive intracytoplasmic lumen formation. All cases were treated by surgical excision. Follow-up information was available in nine patients; seven patients were alive and well without evidence of disease 2-21 years after diagnosis (mean follow-up, 8 years); one patient had a recurrence after 1 year and died due to complications of surgery, and another patient died after 1 year of undetermined causes. Despite their often ominous clinical, radiological, and pathological features, epithelioid hemangioendotheliomas arising in the anterior mediastinum appear to behave as low-grade malignant neoplasms that may be adequately controlled in most instances by surgery alone.
Adenoid cystic carcinoma (ACC) of the salivary gland is generally an indolent tumor that pursues a protracted clinical course with recurrences and late metastasis. The authors report three cases of ACC with dedifferentiation to high-grade malignant neoplasms. One patient developed dedifferentiated ACC ab initio, with extensive local disease and multiple lymph nodes metastases at first presentation, requiring mutilating surgery. Two patients had dedifferentiated ACC 4 and 10 years, respectively, following excision of the initial uncomplicated ACC; both patients died within 1.5 years after recurrence. Histologically, the dedifferentiated component appeared as a distinct population of anaplastic cells with more abundant cytoplasm, irregular-shaped tumor islands infiltrating a desmoplastic stroma, and total loss of bicellular differentiation characteristic of ACC. The immunophenotypic profile was altered in comparison with the ACC, such as acquisition of strong staining for S100 protein and lack of a myoepithelial component in the two cases that were interpreted as being poorly differentiated adenocarcinoma. One case was a sarcomatoid neoplasm with focal myoepithelial features. Overexpression of p53 protein was demonstrated in the dedifferentiated component in one case, and overexpression of cyclin D1 was seen in two cases. The dedifferentiated component had a higher Ki67 index than did the ACC. To the authors' best knowledge, this report represents the first documentation of dedifferentiation as a form of tumor progression in ACC, which is associated with a sinister clinical outcome.
Desmoplastic small cell tumor (DSCT) is a high-grade malignant neoplasm that shows polyphenotypic differentiation. Its almost exclusive involvement of serosal surfaces (particularly peritoneum) has led to the consideration of a putative "mesothelioblast" as the cell of origin. Although an extraserosal case involving the brain (presumably arising from the dura) has been reported, to date no case primary in the bone or soft tissues has been documented. The authors describe a 34-year-old man who presented with a 3-year history of pain in the right hand and a recently noted mass in the hypothenar area. Open biopsy followed by wide en bloc excision in combination with index ray resection was performed. Subsequently, the patient underwent ipsilateral axillary lymph node dissection. Extensive radiologic workup at the time of presentation and 12 months later revealed no tumor in the chest or abdomen. The patient was treated with an HD-CAV chemotherapy regimen (cyclophosphamide, doxorubicin, vincristine, ifosfamide, etoposide) and was free of tumor until 18 months later, at which time he developed multiple metastases in the lungs. Currently, he is alive with tumor and in poor condition. The histologic sections of the mass displayed the characteristic features of DSCT involving bone and soft tissue. Immunohistochemical stains showed positivity of the tumor cells for muscle marker (desmin), neuroendocrine markers (chromogranin, synaptophysin), and epithelial markers (keratins CAM5.2, AE1:AE3, epithelial membrane antigen). Chimeric transcripts were detected by reverse transcriptase-polymerase chain reaction, indicating the presence of EWS-WT1 gene fusion, which is characteristically associated with DSCT. Sequence analysis showed in-frame fusion of EWS exon 9 to WT1 exon 8--a variant not documented in any other case. This is a unique example of DSCT primary in bone and soft tissues, which raises interesting questions about the histogenesis of this tumor type and its relationship to other small round cell tumors. Although the "mesothelioblast" hypothesis as the origin of DSCTs is attractive, it does not account for the tumors that are located in the brain or, as in this patient, in the soft tissues and bone. In addition, this patient demonstrates a rare variant of EWS-WT1 gene fusion not described in DSCT involving serosal surfaces.
Follicular dendritic cell (FDC) tumors are uncommon neoplasms that can involve lymph nodes or extranodal sites. They can exhibit a broad spectrum of histologic appearances and behavior, but the intra-abdominal ones usually pursue an aggressive course. The purpose of this study was to characterize a distinctive variant of FDC tumor morphologically mimicking inflammatory pseudotumor through analysis of the clinicopathologic features of 11 cases. The patients included 10 women and one man (age range, 19-61 years; median age, 40 years) who presented with abdominal discomfort or pain. Six patients had systemic symptoms such as marked weight loss, fever, or malaise. All tumors occurred in intra-abdominal sites: liver (n = 7), spleen (n = 3), and peripancreatic region (n = 1). Of the nine patients with follow-up data, six were alive and well, one developed recurrence at 9 years, and two had repeated recurrences over many years. Grossly, the tumors were usually solitary and fleshy, punctuated by areas of hemorrhage and necrosis. Histologically, in a background of abundant lymphocytes and plasma cells were dispersed spindle or ovoid cells with vesicular nuclei and distinct nucleoli. The degree of nuclear atypia was variable, and some nuclei could be grotesque or resemble Reed-Sternberg cells. Focally, spindle cell fascicles could be formed. The atypical cells were immunoreactive for FDC markers such as CD21/CD35, CD23, and CNA.42. In situ hybridization for Epstein-Barr virus (EBV)-encoded RNA was positive in all cases, remarkably highlighting the spindle cells and their atypia. EBV-latent membrane protein-1 was expressed commonly, albeit often focally and weakly. Therefore, inflammatory pseudotumor-like FDC tumor represents a distinctive variant of FDC tumor that differs from conventional FDC tumor in the following aspects: marked female predominance; selective localization in intra-abdominal sites, especially the liver and spleen; frequent presence of systemic symptoms; indolent behavior despite an intra-abdominal location; dispersed distribution of tumor cells and prominent lymphoplasmacytic infiltration; and consistent association with EBV.
Myoepitheliomas and mixed tumors were only recently recognized to occur primarily in soft tissue, and only small case numbers have been described. To characterize these tumors further and to evaluate prognostic parameters, 101 myoepithelial tumors of soft tissue were retrieved from the authors' consult files. Hematoxylin and eosin sections were reexamined, immunohistochemistry was performed, and clinical details were obtained from referring physicians. Fifty-three patients were male and 48 female (mean age 38 years; range 3-83 years). Tumor size ranged from 0.7 to 20 cm (mean 4.7 cm). Most tumors arose in the extremities and limb girdles: 41 in the lower limbs, 35 in the upper limbs, 15 in the head and neck, and 10 in the trunk. Fifty-four tumors were situated in subcutis and 37 in deep soft tissue (depth unstated in 10). Most cases were grossly well circumscribed; 43 showed microscopically infiltrative margins. Histologically, most tumors were lobulated, composed of cords or nests of epithelioid, ovoid, or spindled cells with a variably reticular architecture and a chondromyxoid or collagenous/hyalinized stroma. Eight cases showed a predominantly solid proliferation of spindled or plasmacytoid cells; 17 demonstrated ductular differentiation (mixed tumors). Cartilage was present in 6 cases, 6 contained bone, and 4 others contained both. Mitoses ranged from 0 to 68 per 10 high power fields (mean 4.7 per 10 high power fields). Tumors with benign cytomorphology or mild cytologic atypia (low-grade) were classified as myoepithelioma or mixed tumor, whereas tumors with moderate to severe atypia (high-grade) were classified as myoepithelial carcinoma (epithelioid or spindled cells with vesicular or coarse chromatin, prominent, often large nucleoli, or nuclear pleomorphism) or malignant mixed tumor (cytologically malignant cartilage or bone). Sixty-one cases were myoepitheliomas or mixed tumors, and 40 were myoepithelial carcinomas or malignant mixed tumors. By immunohistochemistry, all cases with available material were reactive for epithelial markers (keratins and/or epithelial membrane antigen): 90 of 97 (93%) expressed keratins (most often AE1/AE3 or PAN-K), 84 of 97 (87%) S-100 protein, 44 of 51 (86%) calponin, 52 of 83 (63%) epithelial membrane antigen, 40 of 87 (46%) glial fibrillary acidic protein, 27 of 75 (36%) smooth muscle actin, 15 of 66 (23%) p63, and 7 of 51 (14%) desmin. Follow-up was available for 64 patients. Among 33 cases with benign or low-grade cytology (mean follow-up 36 months; range 4-168 months), 6 recurred locally (18%) and none metastasized. No clinical or histologic features correlated with recurrence. Among 31 cytologically malignant cases (mean follow-up 50 months; range 4-252 months), 13 recurred locally (42%) and 10 metastasized (32%); so far, 4 patients have died of metastatic tumor. This study expands the spectrum of myoepithelial tumors of soft tissue to include myoepithelial carcinomas and malignant mixed tumors, which pursue an aggressive clinical course. Although the majority of morphologically benign or low-grade myoepithelial neoplasms of soft tissue behave in a benign fashion, there is an approximate 20% risk for local recurrence.
We describe 24 cases of polypoid endometriosis, most of which were referred because of problems in differential diagnosis, particularly distinction from a low-grade müllerian neoplasm. The patients were 23 to 78 years (mean 52.5 years) of age. Seven patients were on unopposed estrogen, four on combined estrogen-progestin therapy, and one patient had a synchronous ovarian thecoma. The most common clinical presentations were a pelvic mass, vaginal polypoid masses, and large bowel obstruction. In some cases, the intraoperative findings suggested a neoplasm. Sites of involvement in order of frequency included colon, ovary, uterine serosa, cervical and/or vaginal mucosa, ureter, fallopian tube, omentum, bladder, paraurethral and paravaginal soft tissue, and retroperitoneum. Multiple sites were involved in seven cases. Five cases occurred within ovarian or extraovarian endometriotic cysts. The lesions ranged up to 14 cm in size and formed polypoid, pink, gray or tan, masses. On microscopic examination, the polypoid masses were composed of an admixture of endometriotic glands and stroma. A variety of glandular architectural patterns were observed, sometimes in combination, most commonly cystic and noncystic simple hyperplasia, but also simple or complex hyperplasia with atypia, disordered proliferative, and cystic atrophy. Various types of epithelial metaplasia (tubal, mucinous, squamous, papillary syncytial metaplasia) were common. Hemorrhage, fibrosis, prominent thick-walled blood vessels, hemosiderin-laden histiocytes, and decidual change were also present in some cases. Eighteen cases were associated with usual (nonpolypoid) endometriosis. In one case, polypoid endometriosis merged with a mucinous borderline tumor of endocervical-type. In all but two cases, polypoid endometriosis lacked periglandular stromal hypercellularity, stromal atypia, and intraglandular stromal papillae, helping distinguish it from adenosarcoma. Focal intraglandular stromal papillae were noted in two cases with focal mild periglandular stromal hypercellularity in one of them, but no stromal atypia was present in either case. Follow-up data in 17 patients indicated that 15 patients were alive without evidence of residual disease, 1 was alive with residual endometriosis, and 1 died of other causes. In conclusion, polypoid endometriosis is a rare manifestation of endometriosis that may be mistaken for a neoplasm on clinical, intraoperative, or pathologic assessment. Some cases may be attributable to exogenous hormones or hyperestrinism and, like conventional endometriosis, some may evolve into a premalignant or, rarely, a neoplastic lesion. The main lesion in the differential is a müllerian (mesodermal) adenosarcoma.
Tissue samples from 49 women with seven benign and 42 malignant ovarian tumors were examined by means of DNA flow cytometry (FCM). The FCM data (DNA-ploidy and the number of S-phase fractions) were compared with the International Federation of Gynecology and Obstetrics (FIGO) stage, the histologic grade of differentiation and in some cases with the clinical outcome. The benign ovarian tumors were all diploid with a mean of 2.1% (+/- 1.66) S-phase fractions. Adenocarcinomas with the histologic grade 1 were diploid and had a mean of 2.1% (+/- 1.17) S-phase fractions. Grade 2 adenocarcinomas were aneuploid in eight of nine cases and revealed an increased proliferative activity (7.7% +/- 2.67 S-phase fractions). A high number of aneuploid cases (nine of 13) and an increased DNA synthesis were found in grade 3 adenocarcinomas (12.0% +/- 5.72 S-phase fractions). Four of six malignant nonepithelial tumors also had high numbers of S-phase fractions (9.7-14.5%). A significant correlation between the histologic grade and the DNA synthesis, FIGO stage, and DNA-ploidy was found. DNA-FCM may be used as an additional diagnostic tool supplementing routine histopathologic examination of ovarian tumors for better biological characterization, especially for those with uncertain grading, for grade 2 neoplasms, and for malignant nonepithelial tumors.
Epithelioid hemangioendothelioma (EH) is a rare, low-grade, malignant neoplasm of vascular origin that may develop at different sites, such as in the soft tissue, lungs, or liver. We report the case of a 21-year-old female with primary EH of the liver treated by liver transplantation and review the available literature on EH. This patient developed symptomatic recurrence of the tumor in the pelvis 2 months posttransplant. Treatment with interferon alpha-2b resulted in substantial regression of the pelvic metastases and alleviation of symptoms, but the patient developed graft rejection and died of associated complications 16 months posttransplant. This report is the first showing the efficacy of interferon in this setting.
PURPOSE: We reported a nomogram and subsequently a corrected version for predicting the probability of positive biopsy in men with 1 or more prior negative biopsies. In this study we assessed the validity of this nomogram when applied to an external dataset. MATERIALS AND METHODS: There were 230 patients from the Brooklyn Veterans Administration Medical Center who underwent 1 or more repeat biopsies after initial negative biopsy from January 1993 to June 2003. Predictor variables studied in the nomogram were patient age, family history of prostate cancer, digital rectal examination, serum prostate specific antigen, prostate specific antigen slope, months from initial negative biopsy session, months from previous negative biopsy session, cumulative number of negative cores previously taken and history of high grade intraepithelial neoplasm or atypical small acinar proliferation. We calculated the nomogram predicted probability in each patient. These predicted outcomes were compared with actual biopsy results. Area under the ROC curve was calculated as a measure of discrimination. Calibration was assessed graphically. RESULTS: We evaluated a total of 356 repeat biopsies in 230 patients (mean 2.56 total biopsies per patient). The mean number of total cores per patient was 17.9. There were 78 positive biopsies. The area under the ROC curve was 0.71, which was greater than any single risk factor. Nomogram calibration appeared to be good. CONCLUSIONS: Our corrected nomogram for predicting positive repeat biopsy performed well when applied to a sample of men at the Brooklyn Veterans Administration Medical Center. This nomogram can provide important additional information to aid the urologist and patient with a negative biopsy in evaluating clinical options.
The current classification system of renal tumors is based on morphologic criteria, as supported by genetic findings. We present a group of previously unclassified tumors with similar morphologic and genetic features, suggesting a new entity within renal neoplasms. Seven renal tumors from five patients (ages 31-67 years) were analyzed. All cases were stained with periodic acid-Schiff, Hale's colloidal iron (HCI), and Alcian blue (AB) at pH 2.5/1.0 with and without hyaluronidase (HA) digestion. Immunohistochemical (IHC) stains were performed for CK8, CK18, CK19, vimentin, villin, Tamm-Horsfall protein (THP), renal cell carcinoma marker (RCC), epithelial membrane antigen (EMA), ulex europaeus agglutinin (UEA-1), soy bean agglutinin (SBA), peanut agglutinin (PNA), and MIB-1. Comparative genomic hybridization (CGH) and loss of heterozygosity (LOH) studies were performed on all cases. All tumors showed circumscribed growth, a tubular growth pattern with focal solid areas, no significant nuclear atypia and absence of necrosis, desmoplasia, or inflammation. Abundant extracellular mucin was present. Immunohistochemistry stains support collecting duct origin (EMA+, PNA+, SBA+/-, CK 8/18/19+, vimentin+/-, UEA-1-, RCC-, villin-, THP-). The proliferative rate was low (<1%). CGH showed multiple consistent chromosomal losses (-1,-4, -6, -8, -9, -13, -14, -15, -22). Clinical outcome was favorable, with recurrences but no known distant metastases or death of disease. These findings are distinct from all previously classified renal neoplasms. Our data suggest the presence of a unique tumor entity within tumors of probable collecting duct origin: tubular-mucinous renal tumors of low malignant potential.
Kaposi's sarcoma (KS) is a low grade malignant neoplasm which shows invasive growth and often occurs in immunosuppressed patients with the Acquired Immune Deficiency Syndrome (AIDS; epidemic KS). It is also found in elderly men where it is usually limited to the skin (classic KS). The present study investigated the chemotaxis and invasive migration of epidemic KS cells in vitro and compared them to cells grown from classic KS lesions and to fibroblasts. Epidemic KS cells demonstrated invasive migration through reconstituted basement membrane (Matrigel) as well as through interstitial connective tissue (collagen I) in early passages, whereas fibroblasts did not invade either barrier. Epidemic KS cells in late passages did not show any invasive migration. Following pretreatment with tumour necrosis factor alpha (TNF-alpha) there was no enhanced migration through the Matrigel and collagen I for epidemic KS cells, whereas classic KS cells showed an increased migration through the type I collagen barrier.
Papillary glioneuronal tumor is a recently identified low-grade brain neoplasm classified as variant of ganglioglioma. Its salient morphological characteristics are the presence of pseudopapillary structures composed of blood vessels, often hyalinized, lined by uniform small astrocytes and a proliferation of neurocytic cells, eventually admixed with ganglioid and ganglion cells. We present a case of papillary glioneuronal tumor occurring in a 15-year-old female with an unusual hemorrhagic onset. The clinical, morphological and immunohistochemical features are discussed and the published literature is reviewed. This article proposes that papillary glioneuronal tumor should be included in the differential diagnosis of patients with tumoral related brain hemorrhage.
Pure protoplasmic astrocytomas are a group of rarely encountered low grade astrocytic neoplasms. Relatively few studies have specifically examined this subset of tumors. A series of 18 protoplasmic astrocytomas in 14 males and four females (age range 2.5-52, mean 22 years) were studied in order to examine MIB1 (a marker of cell proliferation) and p53 (a tumor suppressor gene) immunoreactivity. All patients presented with seizures (mean duration 94 months) and three with headaches also. Eight tumors were located in the temporal lobe and six in the frontal lobe. All tumors were characterized by a proliferation of astrocytes with round nuclear contours arranged against a microcystic background. Only rare foci of mild vascular proliferation (3 tumors), rare mitotic figures (1 tumor), and mild nuclear atypia (3 tumors) were observed. Most tumors were primarily cortical in location. Necrosis was not seen in any of the tumors. MIB1 indices (number of MIB1 positive tumor cells/1000 tumor cells evaluated x 100) ranged from 0 to 4.3 (mean 0.7); in five tumors, no MIB1 staining was observed. p53 immunoreactivity was noted in 5 of 18 tumors (28%). Five patients received adjuvant radiation therapy and one adjuvant chemotherapy. At last known follow-up, 11 patients are alive with no evidence of residual tumor (mean 70 months), six patients are alive with evidence of residual tumor (mean 58 months), and one patient died of complications unrelated to the tumor (36 months) postoperatively. Based on these findings, the conclusions presented are as follows: (i) MIB1 indices are generally low in these tumors, corroborating the clinical impression of a slow growing neoplasm; and (ii) p53 immunoreactivity is observed in a minority of protoplasmic astrocytomas.