Fibrous dysplasia and cemento-ossifying fibroma. A histologic spectrum

Fibrous dysplasia (FD) and cemento-ossifying fibroma (COF) are benign fibro-osseous lesions that are generally considered to be separate entities, distinguished by histologic and radiographic features. In our experience, some lesions lack the classic clinical, radiographic, or pathologic features of FD or COF and rather have overlapping features of both entities. Consequently, these cases are frequently diagnosed nonspecifically as fibro-osseous lesions. We examined 56 gnathic and extragnathic fibro-osseous lesions of bone morphologically, clinically, and radiographically to determine whether they can be reliably distinguished and whether their distinction has any clinical or prognostic significance. The lesions exhibited a broad morphologic spectrum of patterns ranging from pure FD (24 cases) to pure COF (10 cases). Twenty-two lesions contained a mixture of both patterns; 11 lesions with a predominant FD pattern contained calcified spherules histologically indistinguishable from those characteristically seen in COF. The remaining 11 lesions contained areas of typical FD adjacent to areas of COF. The lesions examined also demonstrated considerable radiographic overlap, and FD could not be reliably distinguished from COF. The recurrence rate was low for all lesions regardless of the histologic pattern. Because of histologic and radiographic overlap and similar low recurrence rate of FD and COF, we consider them to be related lesions, and COF is probably an opposing end of a morphologic spectrum of FD.

Core needle biopsy and fine-needle aspiration in the diagnosis of bone and soft-tissue lesions

Although core needle biopsy (CNB) and fine needle aspiration (FNA) procedures are widely used for the diagnosis of epithelial neoplasms, these procedures have not gained popularity on patients suspected of having bone or soft-tissue neoplasms. This article describes the University of Texas, M.D. Anderson Cancer Center experience with CNB and FNA procedures in bone and soft tissue performed in over 800 patients.

Ductal carcinoma in situ treated with lumpectomy and irradiation: histopathological analysis of 49 specimens with emphasis on risk factors and long term results

Forty-nine women with ductal carcinoma in situ (DCIS) treated with lumpectomy and irradiation were studied retrospectively. The median age was 50 years (range, 29 to 73 years) and the median follow-up time from initiation of therapy was 86 months (range, 17 to 230 months). Twelve patients presented with palpable masses (0.4 to 4 cm), three with breast thickening, and three with nipple discharge. In 31 patients the tumors were detected by mammography. Intraoperatively, excision of lesions was confirmed by specimen x-ray (38 specimens) or gross inspection (five specimens) and was recorded to be complete. No record was available in the other six patients. Margins of excision free of DCIS were microscopically confirmed in 25 specimens. The size of impalpable DCIS lesions recorded in 25 patients ranged from 0.4 to 5.0 cm (mean, 1.5 cm). Using Lagios' classification system, there were 18 classic comedocarcinomas, high nuclear grade (NG) with necrosis; seven cribriform/papillary, high NG with necrosis; 17 cribriform/micropapillary, intermediate NG with or without necrosis; and seven cribriform/micropapillary, low NG without necrosis. In two patients residual malignant calcifications were present on the postoperative mammogram. Disease recurred in the treated breast at the site of incision in five patients at 18 months and 8, 11, and 12 (two patients) years from initial therapy. The rate of local disease recurrence was 2% at 5 years and 6% at 10 years; three recurrences showed invasive ductal carcinoma and two were DCIS. To evaluate risk factors the following characteristics were considered: necrosis, NG, histological type, periductal fibrosis, periductal lymphoid infiltrate, margin status, age, and method of tumor detection. The end points chosen were recurrence and death from any cause (because only one patient died of disease). Although the recurrences were attributed to residual disease in two patients, of the clinical and pathological parameters evaluated, only periductal fibrosis showed a significant relationship with outcome, with a P value < or = .05 by the Wilcoxon test. On the other hand, using the proportional hazards model, necrosis was a significant predictor for recurrence (P = .02), as was the pair fibrosis and tumor detection when taken together (P = .05). Fibrosis significantly associated with high NG, Lagios' histological subtypes I and II, periductal lymphoid infiltrate, and necrosis (P < or = .0006).(ABSTRACT TRUNCATED AT 400 WORDS)

Detection of residual prostate cancer after external radiotherapy. Role of prostate specific antigen and transrectal ultrasonography

BACKGROUND

Although the incidence of positive post-radiotherapy biopsies has been reported, the range is considerable (19-93%) and depends partly on patient-selection criteria. In addition, the prognostic significance of transrectal ultrasonography (TRUS) and prostate specific antigen (PSA) used alone and in combination in predicting residual cancer after radiotherapy has yet to be determined.

METHODS

Transrectal ultrasonography-guided prostate biopsies were performed on 31 unselected patients with prostate cancer 34-77 months (mean, 51 months) after definitive external beam radiotherapy was completed. Biopsy results were compared for pre- and posttreatment parameters (clinical stage, grade, PSA, and TRUS).

RESULTS

In 22 patients (71%), residual cancer was detected histologically by biopsy. All but one patient (12/13, 92%) with a pretherapy PSA value greater than 10 ng/mL had a positive biopsy compared with 50% of those (7/14) with a pretherapy PSA value less than or equal to 10 (P < 0.05). After radiotherapy, a positive biopsy was noted for 15 of 16 patients (94%) with a PSA value greater than 2 and in 20 of 23 (87%) of those with abnormal TRUS findings (P < 0.01 and P < 0.005, respectively).

CONCLUSIONS

The most clinically useful model for predicting histologically identifiable residual cancer was either a serum PSA value greater than 2 or a PSA value less than or equal to 2 and abnormal TRUS findings. The positive and negative predictive values of the model were 84% and 83%, respectively. The model predicted biopsy results correctly in 26 of 31 patients (84%). Transrectal ultrasonography is recommended as a diagnostic tool for patients whose PSA level ranges from a detectable level to less than or equal to 2 ng/mL.

DNA and RNA content analysis by flow cytometry in the pathobiologic assessment of bone tumors

Studies of simultaneous DNA and RNA contents by flow cytometry in hematologic and some solid neoplasms have been shown to provide information that may be useful in the pathobiological evaluation of these neoplasms. We contend that similar analysis may be equally valuable in assessing bone tumors. Our data revealed significant statistical differences in DNA ploidy and proliferative fraction between benign and malignant bone neoplasms. Benign tumors manifested predominantly DNA diploidy and low proliferative activity, whereas the majority of malignant tumors were DNA aneuploid and showed high proliferation rate. No significant difference in the RNA content between different histopathologic categories was found. We observed, however, a distinct and consistently high RNA content pattern in giant cell tumors, aneurysmal bone cysts, and chondroblastomas that may be useful in their differential diagnosis. Analysis of different prognostic factors in malignant tumors indicated that histologic grade and DNA content are a significant prognostic factors. Further analysis of malignant tumors showed that a correlation between the proliferative activity and the clinical outcome in the low grade category and between RNA content and patients' survival in osteosarcomas. Our study also showed that preoperative treatment significantly impacted on the extent of the proliferative fraction in malignant tumors. We conclude that DNA/RNA analysis of bone tumor may assist in: (1) the differential diagnosis of certain bone tumors, (2) evaluation of treatment response, and (3) the biological assessment of osteosarcomas.

Treatment of osteosarcoma with ifosfamide: comparison of response in pediatric patients with recurrent disease versus patients previously untreated: a Pediatric Oncology Group study

This study was designed to test if the activity of a phase II agent, ifosfamide, would have been underestimated if it was tested exclusively in a population of children and young adults with recurrent osteosarcoma. The response rate to ifosfamide was compared in patients younger than 30 years of age with previously untreated osteosarcoma with metastases at diagnosis and/or unresectable primary tumors (stratum 1) with that of patients with recurrent osteosarcoma following adjuvant chemotherapy who were not previously exposed to ifosfamide (stratum 2). Evaluation of response was conducted 3 weeks after two courses of ifosfamide (2400 mg/m2 x 5 days) were administered 3 weeks apart. Nine of 33 (27%) evaluable patients in stratum 1 responded (1 complete and 8 partial responses) to ifosfamide. Among 30 evaluable patients in stratum 2, only 3 (10%) responded (1 complete and 2 partial responses; P = .04) Both groups of patients received equal doses of ifosfamide and experienced comparable toxicities. Results from this study suggest that the activity of new agents will be underestimated if tested in a population of heavily pretreated patients with recurrent disease. When possible, new chemotherapeutic agents should be tested in patients with a poor prognosis who have not been exposed to chemotherapy.

The prognostic importance of Gleason grade in prostatic adenocarcinoma: a long-term follow-up study of 648 patients treated with radiation therapy

PURPOSE

It is common practice to histologically grade adenocarcinoma of the prostate using the Gleason system. Whereas the prognostic utility of this grading is well known, few studies have comprehensively evaluated it for patients undergoing definitive radiation therapy and generally accepted guidelines as to which Gleason grades should be "lumped" have not been established. This study reports the results of univariate and multivariate evaluation of the prognostic significance of Gleason grade in 648 patients followed for a median of 6.5 years after radiation therapy for T1 to T4, N0, or NX, MO prostate cancer.

METHODS AND MATERIALS

The correlation between Gleason grade and local recurrence, metastatic relapse, any disease relapse, and patient survival was evaluated using univariate and multivariate methods. Analysis was also stratified according to whether the grading was assigned on a needle biopsy or on a transurethral resection specimen.

RESULTS

The large number of Gleason grades required grouping of grades for meaningful analysis and we found that a four-tier system (grades 2 and 3, 155 patients; grades 4-6, 290 patients; grade 7, 92 patients; and grades 8-10, 111 patients) correlated best with outcome. In univariate analysis, this four-tier grouping correlated significantly with local recurrence, distant metastases, any relapse, and survival. The incidences of distant metastasis at 10 years were: grades 2 and 3, 13%; grades 4-6, 34%; grade 7, 52%; and, grades 8-10, 63%. The survival rates at 10 years were: grades 2 and 3, 64%; grades 4-6, 60%; grade 7, 46%; and grades 8-10, 24%. In multivariate analysis, Gleason grade was the single most important determinant of outcome for each endpoint. These results applied equally to needle biopsy and transurethral resection specimens.

CONCLUSION

Tumor grade is the single most significant determinant of outcome following radiotherapy for clinically localized prostate cancer. The Gleason system is a valid method for grading tumors to be irradiated. A four-tier grouping into grades 2 and 3, grades 4-6, grade 7, and grades 8-10 appears to be adequate and simple.

Histiocytic reaction in pelvic peritoneum associated with oxidized regenerated cellulose

The authors present five cases of an unusual inflammatory reaction in pelvic peritoneal tissues associated with oxidized regenerated cellulose, a topical hemostatic agent. The findings were observed in specimens from five women who had been treated with oxidized regenerated cellulose during abdominal surgery. Histologically, the lesion was characterized by collections of large cells beneath the mesothelial surface, with small bland nuclei and abundant granular basophilic cytoplasm that stained bright red with mucicarmine. Immunohistochemical studies demonstrated that these cells stained positive for KP1 (CD68) confirming their histiocytic nature, and negative for cytokeratin and S-100 protein excluding the diagnoses of carcinoma and granular cell tumor respectively. Although unlikely, the mucicarmine positivity may be misinterpreted, leading to a erroneous diagnosis of adenocarcinoma. To avoid misdiagnosis, pathologists need to be aware of this lesion.

Micropapillary variant of transitional cell carcinoma of the urinary bladder. Histologic pattern resembling ovarian papillary serous carcinoma

Eighteen cases of transitional cell carcinoma (TCC) of the urinary bladder containing a micropapillary component (MPC) (> 90%, three cases; 50-90%, nine cases; < 50%, six cases) are presented. The patients' mean age was 66.6 years (range, 47-81 years) with a male predominance (male-to-female ratio of 5:1). The MPC was part of the surface noninvasive TCC in 16 cases and part of the invasive portion of the TCC in all 18 cases. Eight patients had metastases, each with a predominant (> or = 50%) MPC in the metastases; local recurrence was documented in one case, and the tumor was locally invasive into pelvic structures in three cases. Histologically, the surface MPC comprised slender, delicate filiform processes or small papillary clusters of tumor cells, whereas the deep MPC was composed of infiltrating tight clusters of micropapillary aggregates that were often present within lacunae. Vascular-lymphatic invasion was consistently present in the micropapillary areas. The cytologic features of the MPC were those of grade 3 TCC. A concurrent TCC in situ was identified in 10 cases, noninvasive papillary TCC component in all cases, and glandular differentiation of the invasive TCC in five cases. The initial stage at presentation was usually high stage: one patient with stage A, nine with stage B, six with stage C, and two with stage D. Follow-up data (mean, 44.8 months; range, 6-96 months) indicated that four patients were alive with disease, seven patients were dead of disease, and there was no evidence of disease in seven patients. In five cases, DNA ploidy analyzed by static image analysis showed nondiploid indices within the micropapillary TCC component, and in three cases the DNA index of the MPC (noninvasive, invasive, or at metastatic site) exceeded the DNA index of the noninvasive papillary TCC. In conclusion, the presence of a MPC in TCC is associated with high-grade and high-stage TCC with a tendency to vascular invasion. Our data suggest that a surface MPC in bladder biopsy specimens is a poor prognostic histologic feature and, if the biopsy does not contain muscularis propria, deeper biopsies should be recommended to determine the presence of muscle invasion.

Heterologous elements in the dedifferentiated component of dedifferentiated liposarcoma

Five cases of dedifferentiated liposarcoma in which heterologous elements were present in the dedifferentiated component are presented. Two patients, men 54 and 66 years of age, had retroperitoneal atypical lipomatous tumors (well-differentiated liposarcomas) that recurred (after 2.5 and 12 years, respectively) as dedifferentiated liposarcomas with rhabdomyosarcomatous elements in the dedifferentiated components. The third patient, a 63-year-old woman, had a retroperitoneal dedifferentiated liposarcoma whose dedifferentiated component demonstrated focal osteoid formation. The fourth patient, a 36-year-old woman, had two seemingly separate retroperitoneal masses, one composed of atypical lipomatous tumor with foci of smooth muscle and the other of leiomyosarcoma; despite the apparent separation, it was thought more logical to consider this a dedifferentiated liposarcoma with leiomyosarcoma as the dedifferentiated component than two unrelated neoplasms. The fifth patient, a 45-year-old man, had a mediastinal dedifferentiated liposarcoma with angiosarcomatous areas in the dedifferentiated component. The relatively short follow-up thus far available on these cases has not demonstrated tumor behavior significantly different from that of dedifferentiated liposarcoma as a whole.

Diffuse embryoma of the testis. An immunohistochemical study of two cases

The authors report the histologic and immunohistochemical findings of two cases of diffuse embryoma of the testis, a distinct form of mixed-germ-cell tumor characterized by diffuse, orderly arrangement of embryonal carcinoma (EC) and yolk sac tumor (YST) with scattered trophoblastic components. The patients were 37 and 38 years old when they presented with a right testicular tumor, which was confined to the testis (stage I) in both cases. Histologically, the tumor was composed predominantly of intimately intermingled EC and YST components in almost equal proportion. The tumor cells were arranged in necklacelike fashion; the EC cells formed glandular structures rimmed by a single cell layer of YST cells. The YST component was highlighted by positive staining for alpha-fetoprotein and strong staining for cytokeratin, whereas the EC component was positive for Ki-1 (BerH2, CD30) antigen, was negative for alpha-fetoprotein, and stained more weakly for cytokeratin. The randomly distributed few trophoblastic elements stained for human chorionic gonadotropin. The patients are alive with no evidence of disease, 11 years and 9 months after surgery, respectively. This newly described but distinct variant of mixed-germ-cell tumor should be differentiated from polyembryoma, which is composed of multiple discrete embryoid bodies.

Tubular seminoma. An immunohistochemical and DNA flow-cytometric study of four cases

The histomorphologic features, immunohistochemical reactivity, and DNA content of four cases of a rare tubular variant of seminoma are presented. These neoplasms were characterized by a predominantly tubular architectural pattern that resembled yolk sac tumor, embryonal carcinoma, and sex cord-stromal tumors. The patients' ages were 15, 24, 27, and 44 years. On initial examination, three patients had painless testicular enlargement, and one had a large retroperitoneal mass and a clinically occult primary testicular tumor. The size of the tumors ranged from 1.7 to 6.0 (mean, 4.0) cm. Microscopically, the tumor cells had a tubular or tubulopapillary pattern that consisted of a single layer of cells, often in a back-to-back arrangement with intervening fibrovascular septa. Areas of classic seminoma were present in all cases. Scattered syncytiotrophoblastic giant cells were seen in two tumors. The tumor cells of both the classic and the tubular components of the seminomas were diffusely positive for placental alkaline phosphatase but were negative for cytokeratin and alpha-fetoprotein. DNA flow-cytometric analysis demonstrated abnormal stemlines with hypotetraploid DNA and a mean DNA index of 1.7 in both the classic and the tubular components. The presence of concurrent areas of classic seminoma, similar cytologic features in the tubular and classic seminoma areas, and the identical immunohistochemical and DNA flow-cytometric findings indicate that tubular seminoma is a histologic variant of seminoma. Although the behavior of the tubular variant appeared not to differ from that of classic seminoma in our small series, its recognition is important in the differential diagnosis and management of testicular masses.

Glomus tumor of the female external genitalia: a report of two cases

Glomus tumors occurring in the external genitalia of two women aged 53 and 46 years, respectively, are reported. One of the tumors was clitoral and the other arose in the periurethral area of the vulva. The diagnosis in one case was supported by immunocytochemical analysis. Electron microscopy was performed on both tumors. Only two glomus tumors involving the female external genitalia have been reported in the literature. The tumors we describe appeared to be morphologically similar to the glomus tumors that typically arise in the distal extremities.

Sarcomatoid carcinoma of the lung. A case with atypical carcinoid and rhabdomyosarcomatous components

Sarcomatoid carcinomas of the lung are uncommon malignant biphasic tumors composed of carcinomatous and sarcomatous components. The carcinomatous component is usually a squamous carcinoma, and the sarcomatous component usually resembles a fibrosarcoma or a malignant fibrous histiocytoma. The presence of rhabdomyoblastic differentiation in such neoplasms is exceedingly rare, with only seven documented cases. This report describes a unique case of sarcomatoid carcinoma in a 52-year-old woman in whom the sarcomatous component of the tumor was a rhabdomyosarcoma and the carcinomatous component was an atypical carcinoid. The authors know of no previous report of a sarcomatoid carcinoma of the lung in which the carcinomatous component is a carcinoid.

Carcinomas metastatic to follicular adenomas of the thyroid gland. Report of two cases

Metastases to the thyroid gland are an uncommon occurrence, and metastasis to a preexisting thyroid neoplasm is even more rare. We report two cases of tumor-to-tumor metastasis where a prostatic and a breast carcinoma metastasized to follicular adenoma of the thyroid gland. The metastatic process in case 1 was initially diagnosed by fine-needle aspiration biopsy and later confirmed with the hemithyroidectomy. Immunostaining for prostate-specific antigen and prostatic acid phosphatase in case 1 and estrogen and progesterone receptors in case 2 demonstrated strong immunoreactivity in the metastatic tumor cells. Flow cytometric DNA analysis of the primary and the metastatic tumors in both cases demonstrated stemline fidelity that supported their association. Our cases exemplify why attention should be given to the possibility of metastasis when distinctly different morphologic features are seen in an otherwise typical tumor and the utility of ancillary tests that may assist in establishing the diagnosis.

Lymphoepithelioma-like carcinoma of the urinary bladder

We report the cases of 11 patients who were treated for undifferentiated carcinoma of the urinary bladder with a prominent lymphoid stroma (lymphoepithelioma-like carcinoma [LELC]). The chief complaint of all 11 patients was hematuria. Their ages ranged from 52 to 79 years (mean of 67). All tumors except one invaded the muscle wall and showed the typical syncytial growth pattern of undifferentiated cells with ill-defined cytoplasmic borders, prominent nucleoli, and numerous mitoses. A significant lymphocytic reaction was an essential component of all these tumors. There were three pure LELC tumors without concurrent invasive transitional-cell carcinoma (TCC) or TCC in situ; these cases morphologically simulated large-cell lymphoma. The remainder were mixed TCC and LELC (five predominant and three focal LELC). The tumor cells were immunoreactive for keratin and showed negative results for leukocyte common antigen. The lymphoid population was an admixture of T cells and B cells with a predominance of T cells. Seven patients (four with predominant and three with focal LELC) were treated with various therapeutic methods. Four patients (three with pure and one with predominantly LELC) received only chemotherapy after transurethral resection of the tumor, and follow-up found no evidence of disease for 9-72 months (mean of 38 months). Awareness of an LELC component in a urinary bladder tumor is also important in order to avoid misinterpreting these tumors as malignant lymphoma or severe chronic cystitis. Our data suggest that the pure LELC tumor appears to be morphologically and clinically different from TCC and that it merits recognition as a separate clinicopathologic entity. In addition, there is strong suggestive evidence that it responds to chemotherapy and therefore there is the potential of salvaging bladder function.

Nephrogenic adenoma of the prostatic urethra involving the prostate gland: a clinicopathologic and immunohistochemical study of eight cases

Nephrogenic adenoma (NA) of the prostatic urethra with involvement of the prostate gland can mimic other small-gland proliferations of the prostate, particularly adenocarcinoma of the prostate. To further characterize this lesion and refine diagnostic criteria we retrospectively reviewed the clinicopathologic features and immunohistochemical findings of eight cases of NA involving the prostate gland seen at The University of Texas M.D. Anderson Cancer Center from 1987 to 1992. The patients' ages ranged from 44 to 76 years (average age, 65 years). Six patients had lower genitourinary tract operations. Follow-up information was available for six patients (follow-up period, 5 to 38 months); only one patient had clinical evidence of recurrence (5 months after surgery). The remaining patients were alive and well with no evidence of disease. Histologically, NA was characterized by a proliferation of small tubules lined by a single layer of cuboidal or flattened cells with clear or eosinophilic cytoplasm. The nuclei were round with fine chromatin and there was no mitotic activity. Nucleoli were generally small, but occasionally prominent. All NA extended into the prostatic parenchyma, raising the possibility that these lesions may represent prostatic small-gland proliferations, particularly prostate adenocarcinoma. However, all cases tested were negative for prostate-specific antigen and prostatic acid phosphatase. Our findings indicate that the histologic features and the use of prostate-specific antigen and prostatic acid phosphatase immunostains will help to distinguish NA of the urethra involving the prostate from other small-gland proliferations (eg, small-acinar adenocarcinoma of the prostate, clear cell adenocarcinoma of the urethra, sclerosing adenosis, atypical adenomatous hyperplasia, florid hyperplasia of mesonephric remnants, simple lobular atrophy, and incomplete basal cell hyperplasia).

Assessment of Ki-67-derived tumor proliferative activity in colorectal adenocarcinomas

Analysis of tumor growth fraction (TGF) has become essential as cell cycle-directed modalities have been increasingly used for the treatment of solid neoplasms. We studied TGF in fresh tissue samples from 74 surgically resected colorectal carcinomas (50 colon and 24 rectum; 44 men and 30 women) by flow cytometry (FCM) and by immunostaining using Ki-67 monoclonal antibody. In 12 cases, samples of uninvolved colonic mucosa adjacent to tumor (transitional mucosa) and samples of normal mucosa (at least 5 cm away from tumor) were available for growth fraction analysis. The mean Ki-67 and S-phase values were 17.1% (range, 0-60%) and 17.5% (range, 3-39%), respectively. The mean percentage of Ki-67 positivity in tumor samples from women was significantly lower than that in samples from men (P = 0.001). Ki-67-derived TGF values, however, did not correlate with patient age, lymph node status, or tumor size, site, stage, degree of differentiation, or DNA ploidy. The correlation between Ki-67-derived and FCM-derived TGF values was statistically significant (P = 0.001) but marginal (R = 0.35). In both transitional and normal colonic mucosa samples, Ki-67 positivity was mainly confined to the lower half of the crypts, and their growth fraction values were significantly lower than those of tumor tissue; however, there was no difference in values between transitional and normal mucosae. Our results indicate that Ki-67-derived TGF does not correlate with known prognostic factors for colorectal carcinoma; however, long-term follow-up information will be necessary to define the clinical value of Ki-67 staining.

Giant solitary synovial chondromatosis

The purpose of this report is to describe giant solitary synovial chondromatosis, a previously unrecognized feature of synovial chondromatosis that may histologically and radiographically mimic a malignant neoplasm. Giant solitary synovial chondroma is an intra- and/or extraarticular lesion measuring over 1 cm in size and sometimes as large as 20 cm. The radiographic appearance is that of a large, well-marginated mass either of irregular feathery calcification from coalescence of multiple small synovial chondromas, or a rounded calcified mass from the growth of a single synovial chondroma. Radiographically, giant solitary synovial chondromatosis may appear similar to chondrosarcoma and parosteal osteosarcoma.

Electron microscopy in the diagnosis of small round cell tumors of bone

Small round cell tumors involving bone can present problems in differential diagnosis by light microscopy. In exploring the role of electron microscopy in this situation, seven small cell osteosarcomas and seven mesenchymal chondrosarcomas were examined by electron microscopy and compared with typical and atypical Ewing's sarcomas. There is much overlap in the ultrastructural features of these tumors, but electron microscopy is helpful to establish or confirm a diagnosis of typical Ewing's sarcoma and, if representative matrix is present, of small cell osteosarcoma.

Case report 806: Monostotic Paget's disease of the hand (fifth metacarpal)

Monostotic Paget's disease of bone is an uncommon disease, reported in the hand in only a few instances. We have described an additional case involving a metacarpal bone in a 43-year-old man. We believe this disease should be considered in the radiological differential diagnosis of lytic expansile, subchondral lesions of the hand.