Hibernoma

Hibernoma is a rare, benign soft tissue tumor composed of brown fat. A 42-year-old white man presented with an enlarging soft tissue mass located in his left medial thigh. This was evaluated radiographically by CT as well as MR imaging. An open biopsy revealed a hibernoma. The mass was subsequently excised in its entirety, maintaining a cuff of normal tissue. The patient has done very well postoperatively. Although nearly 100 cases have been reported, this case is presented to review the clinical and pathological presentation of this tumor and to describe its MR imaging characteristics.

Comparative age-related acute and chronic pulmonary oxygen tolerance in rats

Young rats are thought to be more tolerant to hyperoxia. We propose that this may not be proven and depends on how tolerance is defined. We assessed oxygen tolerance in Sprague-Dawley rats from birth to maturity by comparing survival, lung water, antioxidant enzyme activity, lung morphometrics, heart weight, and arterial blood gases in newborn and 27-, 44-, 48-, and 96-day-old rats exposed to 100% O2 or room air for 22 days. Some 96-day-old rats (rest group) received only 50% O2 between 48 and 72 h. Mortality after 5 days of O2 was 0% in newborn and 27-day-old rats and 27% in 44-day-old rats but was > 80% in 48- and 96-day-old rats. Between 5 and 22 days, the death rate was 100% in newborns, 25% in 27-day-old rats, and 0% in 44- to 96-day-old rats. Death occurred when lung water was > 84% except in newborns, which tolerated high lung water for the first 7 days. In chronically exposed 44- and 96-day-old rats, lung water returned to normal. Enzyme activity increased with O2 at all ages but did not relate to survival. In 96-day-old rats, the initial increase was suppressed on day 3. All chronically O2-exposed rats had minimal nonvascular parenchymal changes but developed right ventricular hypertrophy and increased alveolar ductal artery muscularization and lost alveolar capillaries. The most mature rats were least affected. In O2, there was pulmonary insufficiency the first 3 days, followed by recovery, and later hypercarbia and decreased arterial PO2. We conclude that young rats, 0-44 days old, are more O2 tolerant for 5 days. More mature animals, surviving 5 days, are more tolerant to chronic exposure.

Leiomyosarcoma of the vulva: report of a case

A 52-year-old female presented with a progressively enlarging vulvar mass. Pathological evaluation revealed a high-grade vulvar leiomyosarcoma. Immunohistochemical and ultrastructural studies were performed to support the diagnosis. In an effort to better understand the biology of this tumor additional immunohistochemical studies for the protein product of p53 tumor suppressor gene and estrogen receptor expression by tumor cells, as well as the type of immune cells infiltrating the tumor were performed. Tumor cells showed an overexpression of p53 protein and were estrogen receptor-positive. Macrophages and T and B lymphocytes infiltrated the tumor in moderate numbers with occasional lymphoid aggregate formation. This study is the first attempt to better understand the biology of these tumors.

Subcapital fractures of the femoral neck: prevalence and cause of radiographic appearance simulating pathologic fracture

OBJECTIVE

Subcapital fractures of the femoral neck are common in elderly persons who have osteoporosis. Occasionally, radiographs of the hip in these patients show a radiolucency in the superolateral, subcapital region of the femoral neck that mimics the features of a pathologic fracture. Our purpose was to determine the prevalence of this finding and the anatomic variations of fracture alignment that cause this appearance.

MATERIALS AND METHODS

All subcapital nonpathologic hip fractures (n = 111) that occurred at our institution during a 5-year period were reviewed. Radiographs were available in 100 of these cases. Review of intraoperative biopsy specimens, available in 69 patients, revealed no evidence of neoplasm in any case. In the other patients, follow-up radiographs, clinical evaluation, and pathology reports were used to exclude neoplastic involvement. Preoperative radiographs were analyzed for the presence of findings suggesting a pathologic fracture. Fracture configuration was classified by using the Garden staging system. Cadaveric femurs (n = 6) were fractured and studied radiographically.

RESULTS

Seventeen (17%) of the 100 subcapital fractures had a radiographic appearance similar to that of a pathologic fracture. This finding occurred only with Garden stage III fractures (n = 7, 32% of Garden stage III fractures) or Garden stage IV fractures (n = 10, 24% of Garden stage IV fractures). Study of the cadaveric femoral specimens showed that the radiographic appearance simulating a pathologic fracture was primarily caused by external rotation of the distal fracture fragment and was accentuated by displacement between fracture fragments.

CONCLUSION

The radiographic appearance of subcapital fractures of the femoral neck unrelated to neoplasm is often similar to that of pathologic fractures. This appearance is caused primarily by rotation of the fracture fragments, and the finding is accentuated by displacement. Recognition of the appearance of subcapital hip fractures mimicking pathologic fractures and knowledge of the cause of this finding are important for prescribing appropriate treatment.

Identification of donor melanoma in a renal transplant recipient

A patient with chronic renal failure received a closely matched cadaveric kidney. Approximately 3 months after transplantation, the patient developed a metastatic malignant melanoma. A large retroperitoneal mass consisting of large pleomorphic polygonal neoplastic cells was found close to the donated kidney. This tumor was diagnosed as a malignant melanoma. DNA analysis of this tumor, the donated kidney, and the recipient indicated that the melanoma originated from the donor. Although this is not the first report of a donated melanoma, it is the first report of definitive DNA analysis of the origin of the malignant cells.

Titanium-induced arthropathy associated with polyethylene-metal separation after total joint replacement

Complications of total joint replacements are not infrequent. The authors describe five patients with displacement of the polyethylene component in two knee (metal-backed patellar component) and three hip joint replacements. Clinical, radiographic, surgical, and pathologic findings were reviewed in all cases. Conventional radiographs revealed abnormal position of the metal components in all patients and opaque curvilinear periarticular deposits in four. Arthropathy caused by deposition of small titanium particles from metal friction (in the absence of interposed polyethylene) was pathologically proved to correspond to the periarticular opacity. The subtle radiolucent polyethylene component was identified in all patients; adequate visualization in some cases may necessitate imaging with additional methods such as magnification, phosphor plate, and soft-tissue radiographic techniques; conventional tomography; and arthrography. Early recognition of these abnormalities in patients with painful joint replacements may allow less extensive surgical revision and prevent development of titanium-induced arthropathy.

Immunocytochemical studies of subtypes of pulmonary endocrine cells in diethylnitrosamine-treated rabbits

New Zealand White rabbits were injected subcutaneously with 20 mg/kg body weight of diethylnitrosamine (DEN), twice per week, starting when they were 1 week old. The animals were sacrificed 6 to 12 months after the first injection and lung tissues were processed for light microscopy. Using serotonin (5HT) and neuron specific enolase (NSE) as markers for the endocrine cells, tissue sections were stained immunocytochemically by the avidin-biotin complex method. Numerous neuroepithelial bodies (NEBs) positive for 5HT, but negative for NSE, were seen in the alveolar duct regions of DEN-treated rabbits. On the other hand, an increased number of solitary endocrine cells immunoreactive for NSE was found in bronchial or bronchiolar epithelia. The results indicate that DEN induced increases in two distinct types of endocrine cells: the component cells of NEBs are positive for 5HT and solitary cells are positive for NSE.

Bilateral choroidal neonatal neuroblastoma

We treated a bilateral, well-differentiated neuroblastoma of the choroid in a patient who had congenital abdominal neuroblastoma. Although orbital metastasis of neuroblastoma is common, intraocular metastasis is not. In our patient, there was no amplification of the N-myc oncogene in the tumor of either eye. This is consistent with early-stage primary neuroblastoma. Histologically, the tumors were identical in each eye and well differentiated with Homer Wright rosettes; most neuroblastoma metastases have few rosettes and are composed of more undifferentiated, anaplastic cells. We believe that our patient had bilateral primary tumors and not metastatic tumors.

Chromosomal abnormalities in clear cell sarcoma. Implications for histogenesis

Cytogenetic analysis was performed on three specimens of clear cell sarcoma, a rare neoplasm of uncertain histogenesis. Chromosomal analysis of clear cell sarcoma has not been reported previously. Two of the specimens analyzed consisted of the primary foot lesion and subsequent lymph node metastasis in a 29-year-old male. The other specimen was a primary foot lesion in a 61-year-old male. Clonal abnormalities were detected in all three of the specimens. The significance of these results with regard to the origin of this uncommon neoplasm is discussed.

Diethylnitrosamine-induced pulmonary endocrine cell hyperplasia and its association with adenomatosis and adenocarcinoma in rabbits

Pulmonary endocrine cells are suspected of being the precursors for small cell carcinoma of the lung (SCCL). The purpose of this study was to determine whether Diethylnitrosamine (DEN) can induce SCCL in rabbits. New Zealand white rabbits were injected subcutaneously with 20 mg/kg body weight of DEN, twice per week, starting when they were 1 week old. Controls received saline vehicle only. The animals were sacrificed 6 to 8.5 months after the first injection and lung tissues were processed for light microscopy. Using serotonin (5-HT) as a marker for the endocrine cells, tissue sections were stained immunohistochemically by the avidin-biotin complex method. In both control and DEN-treated animals, serotonin-immunoreactive cells organized into neuroepithelial bodies (NEBs). There was an apparent increase in the size, number, and stainability of NEB in DEN-injected animals. A majority of these NEBs were localized in the alveolar duct region. Small foci of adenomatosis and well-differentiated adenocarcinomas, which sometimes coexisted with hyperplastic pulmonary endocrine cells, were also found in the DEN-treated rabbits.

Small renal neoplasms: clinical, pathologic, and imaging features

Small renal neoplasms are being found more often because of the widespread use of abdominal CT and sonography. Little is known about their natural history. We therefore retrospectively reviewed clinical, pathologic, and imaging findings in 22 patients with surgically confirmed solitary renal neoplasms that were 3 cm or less in diameter. Eighteen lesions were first found by CT, three by sonography, and one by IV urography. Three lesions were discovered because the patients had hematuria. Nineteen were incidental radiologic diagnoses in patients without renal symptoms. Of 22 neoplasms, 15 (68%) were renal cell carcinomas, six (27%) were oncocytomas, and one (5%) was a lymphoma. Fourteen (93%) of the 15 carcinomas were confined to the kidney, and one showed microscopic capsular invasion. Metastases did not develop in any patient with carcinoma, indicating that small carcinomas usually have good prognoses. Patients with carcinomas had a mean follow-up of 42 months. All neoplasms were visible on CT. However, characterization of these lesions sometimes required a combination of CT and sonography and occasionally angiography. The carcinomas, oncocytomas, and solitary renal lymphoma could not be distinguished radiologically. Small renal neoplasms are most often found incidentally by CT performed in patients without renal complaints. Most are low-stage carcinomas, and some are oncocytomas.

Clear cell sarcoma of tendons and aponeuroses: histogenesis and mode of treatment

Clear cell sarcoma of tendons and aponeuroses is a rare, slow-growing malignant tumor arising from the tendons and aponeuroses of the lower extremity, more often in the foot. Although it appears to be a benign tumor, the clear cell sarcoma can be a malignant sarcoma capable of local recurrences or distant metastases. Microscopically, there is a rather distinctive picture characterized by discrete nests and fascicles composed of spindle cells, and a small round-to-ovoid nucleus containing a central prominent basophilic nucleolus. Since there is some controversy over the best way to treat this disease, and since its histogenesis is still unknown, the authors elected to report the case of a 28-year-old white male for three reasons: first, to illustrate that the tumor is of neural crest derivation; second, to show that an ultrastructural evaluation of the tumor is imperative in some cases; and lastly, to suggest that amputation is the treatment of choice in localized disease.

Unilateral renal cystic disease: CT findings

Unilateral renal cystic disease (URCD) is characterized by replacement of most of one kidney by multiple cysts scattered diffusely throughout the parenchyma without the formation of a distinct, encapsulated renal mass. There are no cysts in the opposite kidney or liver. The condition is nonfamilial and does not cause renal functional impairment. We describe the clinical and radiologic findings in two patients with URCD and discuss how the disorder usually can be distinguished from other renal cystic diseases using CT. Absence of a family history of renal cystic disease and the normality of the other kidney help distinguish URCD from autosomal dominant polycystic kidney disease. The diffuse nature of the cysts in URCD and the absence of a distinct encapsulated renal mass help distinguish URCD from cystic renal neoplasms.

Misalignment of lung vessels and alveolar capillary dysplasia: a cause of persistent pulmonary hypertension

Two infants with fatal persistent pulmonary hypertension are described. Morphologically there was misalignment of the lung vessels, with the veins and the arterioles anomalously related, often sharing the same adventitial sheet. The capillaries did not make contact with the alveolar epithelium. The arterioles had increased medial muscle, and there was extension of the arteriolar muscularization to the precapillary level. The fraction of the parenchyma that was septal and connective tissue was increased. The acini had a decreased complexity, with immature alveoli and with a decreased radial alveolar count. The cause appeared to be related to abnormal capillary and venous plexus formation and migration. This syndrome seems to be identical with that described in three previous reports and probably represents a specific cause of persistent pulmonary hypertension.

Mucinous carcinoma of the breast: recurrence 30 years after mastectomy

We have reported a case of mucinous breast carcinoma that recurred in the form of lung and lymph node metastases 30 years after definitive resection. This case emphasizes the indolent nature of this neoplasm and the need to lengthen the period of follow-up for patients with this form of cancer.

Morphologic response of rat Leydig cells to hemicastration

Hemiorchidectomized rats were followed up to 15 days postsurgery for morphologic evaluation of compensatory testicular response and its correlation to serum testosterone levels. Although gross compensatory testicular hypertrophy (CTH) was not noted, an enlarged interstitium was observed with hypertrophy and hyperplasia of Leydig cells with morphologic changes suggestive of increased cellular activity. These histologic changes were accompanied by compensatory testicular hypersecretion (CTHS) illustrated by the return of the serum testosterone levels to near the intact-control value in the later groups. Ultrastructural studies of the Leydig cells indicated an increase in the amount of smooth endoplasmic reticulum as an underlying mechanism for this response. In view of the previously reported normal serum luteinizing hormone levels after hemicastration, the compensatory hyperactivity/hypersecretion should be considered primarily an intrinsic Leydig cell response, not related to changes in the hypothalamo-hypophyseal axis.

Neuroendocrine carcinoma of the parotid gland: a report of two cases with ultrastructural and immunohistochemical studies

Two cases of primary small cell carcinoma of the parotid gland are reported. This rare neoplasm usually presents as a painful or painless mass in the gland. The finding of neurosecretory granules by electron microscopic study, combined with strong immunoreactivity for neuron-specific enolase and chromogranin, confirms the true neuroendocrine origin of the carcinoma. This tumor appears to have a better prognosis than small cell carcinoma of the lung, which it resembles histologically.

Malignant nerve-sheath neoplasms in neurofibromatosis: distinction from benign tumors by using imaging techniques

Malignant peripheral nerve-sheath neoplasms frequently complicate neurofibromatosis causing pain, enlarging masses, or neurologic deficits. However, similar findings sometimes also occur with benign nerve neoplasms. Our study was done retrospectively to determine if imaging techniques can differentiate malignant from benign nerve tumors in neurofibromatosis. Eight patients with symptomatic neoplasms (three benign, five malignant) were studied by CT in eight, MR in six, and 67Ga-citrate scintigraphy in seven. Uptake of 67Ga occurred in all five malignant lesions but not in two benign neoplasms studied. On CT or MR, all eight lesions, including three benign neoplasms, showed inhomogeneities. Of five lesions with irregular, infiltrative margins on CT or MR, four were malignant and one was benign. Of three lesions with smooth margins, one was malignant and two were benign. One malignant neoplasm caused irregular bone destruction. Accordingly, CT and MR could not generally distinguish malignant from benign lesions with certainty. However, both CT and MR provided structural delineation to help surgical planning for both types of lesion. 67Ga scintigraphy appears promising as a screening technique to identify lesions with malignant degeneration in patients with neurofibromatosis. Any area of abnormal radiogallium uptake suggests malignancy warranting further evaluation by CT or MR. Biopsy of any questionable lesion is essential.

Systemic rhabdomyosarcoma presenting as leukemia: case report with ultrastructural study and reviews

A 20-year-old white male was initially suspected clinically and pathologically of having an acute lymphoblastic leukemic process because of fatigue, severe anemia, thrombocytopenia, a leuko-erythroblastic peripheral blood picture, and a diffusely infiltrated bone marrow. Subsequent review of the bone marrow material indicated cytologic features consistent with either an embryonal, undifferentiated small cell mesenchymal malignancy or reticulo-endothelial malignancy. Ultimately, the electron microscopic (EM) study of the tumor proved to be diagnostic of rhabdomyosarcoma. An extensive search for a primary site of rhabdomyosarcoma did not show any lesion, although the genitourinary region was clinically suspected. The clinical course was a rapidly downhill one with extensive bone and CNS involvement. The patient died 5 months later. An autopsy permit was not obtained. This case emphasizes the occasional tendency of rhabdomyosarcoma to masquerade as a hematopoietic malignancy at the time of presentation and the usefulness of EM study in confirming a diagnosis.

Disseminated rhabdomyosarcoma of the urinary bladder in an adult

A rare case of alveolar rhabdomyosarcoma of the urinary bladder, manifested as a systemic disease in a 51-year-old woman, was diagnosed at necropsy. Diffuse lytic bone lesions and extensive bone marrow involvement with a leukoerythroblastic blood picture led to an initial clinical diagnosis of a hematologic malignancy.

Extraskeletal Ewing's sarcoma

A well documented case of extraskeletal Ewing's sarcoma arising in a finger of a 16-year-old man was studied by light microscopy, immunohistochemistry and electron microscopy. The differential diagnoses of similar "round cell neoplasms" are discussed. Emphasis is placed on the distinction between extraskeletal Ewing's sarcoma and peripheral neuroepithelioma.

Superficial spreading malignant melanoma with neurosarcomatous metastasis

A case of neurosarcomatous nodal metastasis of superficial spreading malignant melanoma, without primary site desmoplasia or sarcomatous changes, is reported. Of particular interest regarding the metastasis are: the ultrastructural demonstration of numerous cytoplasmic microtubules, absence of premelanosomes, intense immunohistochemical reaction with S-100 protein antibody, and the presence, at the light microscopic level, of extranodal fibrosis. The primary lesion shows a pre-existing benign nevus and features suggestive of lamellar fibroplasia. The origin and histogenesis of melanocytic desmoplasia, in the context of a neural crest progenitor cell, and of lamellar fibroplasia, are discussed.

Isolated perfused lung histamine release, lipid peroxidation, and tissue superoxide dismutase from rats exposed to normobaric hyperoxia

Female Sprague-Dawley inbred rats were exposed to either 1 atm of 100% O2 for 24 h, or 65% O2 for 5 days, with or without pretreatment with disulfiram, an inhibitor of lung CuZn-SOD. After O2 exposure, the rats were killed, the lungs removed, and isolated perfused lungs (IPLs) prepared. The IPLs were perfused with modified Krebs-Henseleit buffer, and perfusate histamine, malondialdehyde (MDA), and lung tissue CuZn-SOD activity examined. Disulfiram administration decreased the LT50 of O2-exposed rats from 65 to 36 h. Histamine and MDA in the perfusate from the IPL prepared from rats exposed to 100% O2 for 24 h were markedly increased. When rats were pretreated with disulfiram and exposed to 100% O2 for 24 h, histamine and MDA were increased an additional 77% and 45%, respectively. In separate experiments, 100% O2 exposure significantly decreased lung CuZn-SOD activity by 40% while IPL histamine and MDA were significantly increased. However, exposure of rats to 65% O2 for 5 days decreased lung CuZn-SOD by 69% but did not affect IPL histamine release or perfusate MDA. These studies suggest that IPL histamine release and/or MDA may be an early biochemical marker for pulmonary O2 toxicity, that lung CuZn-SOD activity may not be the only determinant in O2 toxicity, and other defense mechanisms may play a vital protective role during sublethal O2 exposures.

Primary mediastinal germinomas in females: a case report and review of the literature

Primary mediastinal germinomas in females are rare. Long-term survival ranges from 50 to 81%, depending on the initial extent of disease. Initial spread occurs intrathoracically and to regional nodes with late hematogenous dissemination. The roles of surgery, radiation therapy, and chemotherapy are discussed.

Microcystic adenoma of the pancreas with myoepithelial cells. A hitherto undescribed morphologic feature

A case of microcystic adenoma (glycogen-rich cystadenoma) of the exocrine pancreas in a 62-year-old white female presenting with adult-onset diabetes mellitus is reported. Clinical, histopathologic, and ultrastructural findings are discussed with particular emphasis on the presence of myoepithelial cells, a morphologic feature not seen in this tumor previously. The controversy over diabetes mellitus as a significant related factor is also discussed.

Juxtacortical osteosarcoma: a radiologic and histologic spectrum

Radiologic and pathologic findings were analyzed in four patients with parosteal osteosarcomas, three with periosteal osteosarcomas and one with a high-grade surface osteosarcoma. Plain film and histologic findings considered together are usually distinctive and permit differentiation of these tumors from each other and from other lesions with which they are frequently confused. Prognosis and management are determined by tumor extent and histologic grade. Computed tomography is more accurate than conventional tomography, angiography, and bone scintigraphy for preoperative determination of tumor extent and for assessing tumor relationships to the bone cortex and medullary cavity. Histologically, parosteal osteosarcomas are usually low-grade, while periosteal and high-grade surface osteosarcomas are generally high-grade tumors and have worse prognoses. High-grade surface osteosarcoma, which is indistinguishable in behavior and histology from classical medullary osteosarcoma, requires more aggressive surgical management than parosteal and periosteal osteosarcomas.

Benign glandular inclusions in the abdominal lymph nodes of a man

The occurrence of benign glandular inclusions in the abdominal lymph nodes of a man is reported. The cells lining the glands were most likely derived from metaplastic mesothelial cells. Awareness of these benign glandular inclusions is essential, in that they simulate metastatic adenocarcinoma morphologically.

Malignant cystosarcoma phyllodes with simultaneous carcinoma in the ipsilateral breast

A malignant cystosarcoma phyllodes, with simultaneous intraductal and infiltrating duct carcinoma involving the surrounding breast tissue, was found in a 31-year-old black woman. Careful histologic examination of the tissue surrounding the cystosarcoma phyllodes is important in detecting coexistent carcinoma.

Thymic carcinoid tumor with Cushing's syndrome. Report of a case with electron microscopic and immunoperoxidase studies for neuron-specific enolase and corticotropin

A partially encapsulated, 11-cm-diameter anterior mediastinal mass was resected from a 26-year-old man who appeared with signs and symptoms of Cushing's syndrome. Electron microscopic study disclosed cytoplasmic neurosecretory granules and positive immunoperoxidase reactions for neuron-specific enolase and corticotropin in the tumor cells. A lymph node metastasis was detected 11/2 years after the operation. It appears that a thymic carcinoid tumor is a specific entity.

Muscular hamartoma of the breast. An electron microscopic study

A rare case of muscular hamartoma of the breast was presented. An electron microscopic study confirmed that the proliferating spindle cells were of smooth muscle cell origin.

Computed tomography of renal oncocytoma

Renal oncocytoma is a relatively rare tumor that has an excellent prognosis and usually may be treated adequately by local resection. Preoperative differentiation from renal cell carcinoma, which requires radical nephrectomy, is thus of importance. The computed tomographic (CT) and pathologic features of three incidentally-detected renal oncocytomas were compared with those of six renal cell carcinomas of comparable size. Renal cell carcinoma appears on CT as a solid mass that generally has an indistinct interface with normal renal parenchyma, a lobulated contour, and a nonhomogeneous pattern of contrast enhancement. These features correlate with the pathologic findings of an irregular tumor margin and the frequent presence of tumor hemorrhage and necrosis. Oncocytoma, on the other hand, generally has a distinct margin, a smooth contour, and a homogeneous appearance on contrast-enhanced CT scans. These findings correlate with a smooth tumor margin and absence of tumor hemorrhage and necrosis on pathologic examination. These features are not pathognomonic of oncocytoma, as angiographic evidence suggests that renal cell carcinoma may show both distinct margination and a homogeneous blush in 6% of cases. However, their demonstration by CT should alert radiologists and surgeons to the possibility that a renal mass may be an oncocytoma. Such a presumptive diagnosis then can lead to a surgical approach that allows for renal-conserving surgery.

Oncocytic carcinoma of the pancreas

A large firm 12.5 cm mass at the tail of pancreas was surgically resected in a 73-year-old white man. The tumor was composed of solid sheets of cells with abundant finely granular eosinophilic cytoplasm. Electron microscopic study revealed tumor cells which were packed with mitochondria, a feature characteristic of the oncocyte. Perineural invasion and direct extension into the parenchyma of the spleen was present, as well as metastasis to a lymph node. There appears not to be a report of a similar case.