Abdominal cryptococcosis in dogs and cats: 38 cases (2000-2018)

INTRODUCTION

To report the clinical presentation, laboratory and imaging findings, treatment and outcome of abdominal cryptococcosis in dogs and cats in Australia.

MATERIALS AND METHODS

Canine and feline cases from Australia were retrospectively identified (2000 to 2018) via laboratory and referral centre searches for abdominal cryptococcosis diagnosed by cytology (needle aspirates) or histopathology (biopsy or necropsy) of abdominal organs/tissues. Signalment, presenting complaints, clinical signs, laboratory findings, medical imaging, latex cryptococcal antigen agglutination test (LCAT) titres, treatment and outcome data was collected.

RESULTS

Thirty-eight cases were included (35 dogs, three cats) in the study. Median age of presentation was 2 years for dogs and 6 years for cats. Common presenting complaints included vomiting (23/38), lethargy (19/38) and inappetence/anorexia (15/38). Abdominal ultrasound (25/38 cases) revealed mesenteric and intestinal lesions in most of the cases. On surgical exploration, seven cases had an intestinal lesion associated with an intussusception. Nineteen cases had a pre-treatment LCAT performed, with a median initial titre of 1:2048 (range 1:2 to 65,536). Twenty-four cases (23 dogs, one cat) received treatment, either medical, surgical or both. Median survival time for cases with combined medical and surgical treatment, surgical treatment alone or medical treatment alone was 730, 140 and 561 days, respectively. Eleven remain alive at the time of follow up.

CLINICAL SIGNIFICANCE

Abdominal cryptococcosis although rare should be a considered as a diagnostic possibility in an especially young dog presenting with gastro-intestinal signs. Older dogs can also present with this condition and should not be euthanised based on imaging alone due to the likenesses with neoplasia. With appropriate treatment and monitoring many dogs may have a prolonged survival period and some may be cured.

Primary Pulmonary Alveolar Soft-part Sarcoma

Alveolar soft-part sarcoma rarely arises in the lung. Only two patients with tumors that were apparently primary in the lung have been documented in the literature. We report an additional case in a 25-year-old woman. The tumor formed a solitary 5 cm, solid mass in the left perihilar region. Clinical examination, radiologic studies, and follow-up examination of more than 1 year have failed to reveal tumor in an extrapul monary location. The light microscopic appearance was typical for alveolar soft-part sarcoma, and crystalloids were identified in the tumor cells by the periodic acid-Schiff stain and by electron microscopy, confirming the diagnosis. Immunocytochemical studies did not show evidence of myogenic, epithelial, or neuroendocrine differentia tion. Int J Surg Pathol 2(1):57-62, 1994

Impact of passive permeability and gut efflux transport on the oral bioavailability of novel series of piperidine-based renin inhibitors in rodents

An oral bioavailability issue encountered during the course of lead optimization in the renin program is described herein. The low F(po) of pyridone analogs was shown to be caused by a combination of poor passive permeability and gut efflux transport. Substitution of pyridone ring for a more lipophilic moiety (logD>1.7) had minimal effect on rMdr1a transport but led to increased passive permeability (P(app)>10 × 10(-6) cm/s), which contributed to overwhelm gut transporters and increase rat F(po). LogD and in vitro passive permeability determination were found to be key in guiding SAR and improve oral exposure of renin inhibitors.

Design and optimization of a substituted amino propanamide series of renin inhibitors for the treatment of hypertension

The discovery and SAR of a new series of substituted amino propanamide renin inhibitors are herein described. This work has led to the preparation of compounds with in vitro and in vivo profiles suitable for further development. Specifically, challenges pertaining to oral bioavailability, covalent binding and time-dependent CYP 3A4 inhibition were overcome thereby culminating in the identification of compound 50 as an optimized renin inhibitor with good efficacy in the hypertensive double-transgenic rat model.

The advantages gained by the use of modern materials in the post operative casting procedure for foot and ankle surgery

BACKGROUND

In June 2006, the post operative plaster immobilisation protocol for patients undergoing hindfoot and ankle surgery, at our institution, changed from multiple plaster changes to the immediate application of a definitive removable and reusable split synthetic cast. This study aims to assess the savings to the hospital and patient, following this change in practice.

METHODS

A retrospective analysis of plaster room records from June 2005 to June 2007 was performed. The difference in cost to the hospital of the two different post operative journeys was then calculated.

RESULTS

Two-hundred and twenty-two patients from 2005 to 2006 were managed at a total cost of 97,125 euro. From 2006 to 2007, 203 patients were managed with the new technique at a total cost of 37,860 euro. The net saving to the hospital of this change in practice was 251 euro per patient and 50,953 euro in total, while 203 patient visits and costs associated therewith were also saved.

CONCLUSIONS

This study demonstrates how small changes in local practice can result in significant financial and temporal savings for hospitals and patients.

Neuroendocrine (Merkel Cell) Carcinomas of the Skin: An Ultrastructural Study of Nine Cases

Nine neuroendocrine tumors of the skin were examined by light and electron microscopy. The patients (7 males and 2 females) had an average age of 57 years. Seven tumors were located in the head and neck region. Light microscopic examination showed sheets of cells. In 4 cases, a tendency to form small groups of cells was observed. Contact with the epidermis was seen in only 2 cases. The dominant ultrastructural feature was the presence of cytoplasmic processes that contained membrane-bound granules 100-200 nm. Three tumors recurred locally, and in 7 patients, regional nodal metastases occurred. Three patients died of disseminated disease.

Monocytic Leukemia with Cutaneous Involvement: Ultrastructural Observations on Unusual Cytoplasmic Complexes

A case of pure monocytic leukemia ("true" histiocytic lymphoma) presented as multiple cutaneous nodules. The cells contained unusual cylindric formations of the rough endoplasmic reticulum that differ from classic ribosomal-lamellar complexes.

Protothecosis in 17 Australian dogs and a review of the canine literature

Systemic protothecosis was diagnosed in 17 Australian dogs between 1988 and 2005. There was a preponderance of young-adult (median 4 years), medium- to large-breed dogs. Females (12/17 cases) and Boxer dogs (7 cases, including 6 purebreds and one Boxer cross) were over-represented. Sixteen of 17 dogs died, with a median survival of four months. A disproportionate number of cases were from coastal Queensland. In most patients, first signs were referable to colitis (11/17 cases), which varied in severity, and was often present for many months before other symptoms developed. Subsequent to dissemination, signs were mostly ocular (12 cases) and/or neurologic (8 cases). Two dogs had signs due to bony lesions. Once dissemination was evident, death or euthanasia transpired quickly. Prototheca organisms had a tropism for the eye, central nervous system (CNS), bone, kidneys and myocardium, tissues with a good blood supply. Microscopic examination and culture of urine (5 cases), cerebrospinal fluid (CSF;1 case), rectal scrapings (4 cases), aspirates or biopsies of eyes (5 cases) and histology of colonic biopsies (6 cases) as well as skin and lymph nodes (2 cases) helped secure a diagnosis. Of the cases where culture was successful, P wickerhamii was isolated from two patients, while P zopfii was isolated from five. P zopfii infections had a more aggressive course. Treatment was not attempted in most cases. Combination therapy with amphotericin B and itraconazole proved effective in two cases, although in one of these treatment should have been for a longer duration. One surviving dog is currently still receiving itraconazole. Protothecosis should be considered in all dogs with refractory colitis, especially in female Boxers.

Prediction of recurrence and nucleolar features in node-negative breast carcinoma, ductal type, grade II. An ultrastructural study

One-third of patients with node-negative breast carcinoma develop a local recurrence that will decisively influence their outcome. We conducted this quantitative ultrastructural study to determine the value of nucleolar features in predicting recurrence of node-negative breast carcinomas. Forty-three node-negative infiltrating duct carcinomas were examined by means of electron microscopy. The number of cells with three or more nucleoli (N3), percentage of nucleoli contacting the nuclear membrane (NC), patient age, tumor size, grading, treatment, follow-up time, development of recurrence, and status were recorded. There were no differences in patient age, tumor grade, or modality of surgical treatment. Significant differences were found among patients with and without recurrence for N3 ( P=0.02), NC ( P=0.01), and tumor size ( P=0.01). For N3, the positive predictive value (PPV) was 64.3, and the negative predictive value (NPV) was 72.4 (sensitivity=52.9%; specificity=80.8%; P=0.04). For NC, the PPV was 62.5, and the NPV was 74.1 (sensitivity=58.8%; specificity=76.9%; P=0.02). For tumor size, the PPV was 66.7, and the NPV was 64.9 (sensitivity=23.5%; specificity=92.3%; P not significant). Using logistic regression analysis, independent predictive value was shown for N3, NC, and tumor size. The number of nucleoli per cell and the number of cells with nucleoli in contact with the nuclear membrane have independent predictive value for the development of recurrence in lymph node-negative infiltrating duct carcinoma of the breast. Although electron microscopy is a highly accurate method, improving the precision of light microscopic techniques would allow more universal assessment of these nucleolar features.

Ultrastructure of the Ewing's sarcoma family of tumors

Specimens of 47 tumors diagnosed by routine light microscopy as Ewing's sarcoma of bone, and 5 similar soft tissue tumors (extraskeletal Ewing's sarcomas), were examined by transmission electron microscopy. Immunohistochemical stains were performed on all the tumors, and pre-therapy and post-therapy specimens from 5 of the patients were compared. Cell and nuclear areas were assessed in 41 cases by cytomorphometry by using low-magnification electron micrographs. DNA ploidy was determined by static cytometry on 51 of the tumors. None of the methods revealed differences between the bone and soft tissue tumors. The ultrastructural spectrum extended imperceptibly from the typical forms to markedly irregular variants, and was much broader than could be anticipated from the light microscopy. Neural features were observed but they were not common. Comparison of the Ewing's sarcomas with a group of other small round cell tumors (rhabdomyosarcoma, neuroblastoma, small cell carcinoma) using the same techniques showed that they have similar cell and nuclear areas despite the obvious differences in their immunophenotypes and ultrastructure. The collective findings are in keeping with the currently favored view that Ewing's sarcoma and peripheral primitive neuro-ectodermal tumor are the extremes in a morphologic continuum within which neural differentiation ranges from absent to prominent.

Malignant fibrous histiocytoma: an ultrastructural perspective

Malignant fibrous histiocytoma is a frequent diagnosis, but the relationship of the tumors to histologically similar soft tissue neoplasms is controversial. In this study, 157 examples representing the 4 main subtypes were reviewed by light microscopy and each tumor was studied with the electron microscope. Immunohistochemical stains were performed on 77 tumors. Electron micrographs on 100 fibrosarcomas were reviewed for comparison. Malignant fibrous histiocytomas often closely resemble fibrosarcomas at the ultrastructural level and differences between the two are generally of degree only. Evidence for true histiocytic differentiation was not found. The immunohistochemical results did not contradict the authors' impression from electron microscopy that malignant fibrous histiocytoma forms part of the histologic spectrum of tumors of fibroblasts.

Molecular changes in the bronchial epithelium of patients with small cell lung cancer

To better understand the pathways involved in the pathogenesis of small cell lung carcinoma (SCLC), we compared the patterns of molecular changes present in these tumors and their accompanying bronchial epithelium with those present in the other two major types of lung cancer [squamous cell carcinoma (SQC) and adenocarcinoma (ADC)]. We obtained DNA from 68 microdissected invasive lung tumors (22 SCLCs, 21 ADCs, and, 25 SQCs) and 119 noncontiguous foci of histologically normal or hyperplastic epithelia from 10 tumors of each histological type. We determined loss of heterozygosity and microsatellite alterations at 12 chromosomal regions frequently deleted in lung cancers using 19 polymorphic microsatellite markers. Our major findings are as follows: (a) the mean index of allelic loss in SCLC (0.85) and SQC (0.71) tumors was higher than that in ADC (0.39) tumors; (b) although there was considerable overlap, each tumor type had a characteristic pattern of allelic loss; (c) most samples of bronchial epithelium accompanying SCLC (90%) had allelic loss at one or more loci compared with samples accompanying SQC (54%) or ADC (10%); (d) the mean index of allelic loss was much higher in bronchial epithelial samples from SCLC (0.27) than in those from SQC (0.08) or ADC (0.01); and (e) although the mean indices of microsatellite alterations in the tumor types were similar, the bronchial epithelial samples accompanying SCLC had a 10-fold higher mean index (0.063) than those accompanying SQC (0.006) or ADC (0.006). Our findings indicate that extensive genetic damage in the accompanying normal and hyperplastic bronchial epithelium is characteristic of SCLC tumors and suggest major differences in the pathogenesis of the three major lung cancer types.

Acinar cell carcinoma of the pancreas

Four cases of acinar cell carcinoma of the pancreas are reported. An acinar cell carcinoma can resemble an islet cell tumor by routine light microscopy but the two differ considerably in their fine structure and immunostaining properties. Although cells of both tumors contain numerous dense-core granules, their size ranges are different, and atypical forms occur in the acinar cell tumors, including elongated bodies filled with filaments. Many mitochondria-rough endoplasmic reticulum complexes were present in one tumor. In a liver metastasis, nests of endocrine cells were discovered amid the groups of acinar cells, and some of the endocrine granules contained rectangular cores.

Brenner tumor of the ovary: a comparative immunohistochemical and ultrastructural study with transitional cell carcinoma of the bladder

Because of a fancied light microscopic resemblance to transitional epithelium (urothelium), Brenner tumor (BT) of the ovary is commonly described as a transitional cell neoplasm. An inability to detect a great deal of similarity between the two at the ultrastructural level prompted this electron microscopic study comparing 3 benign Brenner tumors with normal urothelium and 6 transitional cell carcinomas (TCC) of varying histologic grade from the urinary bladder. To complement the ultrastructural observations, the immunophenotype of 8 benign BTs was evaluated together with that of 12 TCCs of the bladder using antibodies to thrombomodulin (TM), cytokeratin 20, cytokeratin 7, and carcinoembryonic antigen (CEA), all of which have been shown to react with TCCs of urothelial origin. At the ultrastructural level, there was only limited evidence of a morphologic likeness between the epithelial cells of BTs and those of the benign or neoplastic urothelium. The immunophenotype of the two tumors also differed significantly in that there was no reactivity for TM or cytokeratin 20 in the BTs, while these markers were expressed in the TCCs. Both BTs and TCCs were positive for cytokeratin 7 and may express CEA.

Pigmented carcinoma of the breast: an ultrastructural study

A pigmented skin lesion on a breast removed for carcinoma resembled melanoma by routine light microscopy, but correlation with immunohistochemistry and electron microscopy established that carcinoma cells within the upper dermis were intermingled with a proliferation of non-neoplastic melanocytic cells. Ultrastructurally, the tumor cells possessed desmosomes and intracytoplasmic lumina and mature melanosomes were present in their cytoplasm. The melanocytic cells were identified as melanocytes or melanophages, and it was concluded that the tumor in the skin was a passively pigmented carcinoma and not a melanoma or metaplastic breast carcinoma.

Clear cell sarcoma of kidney in an adolescent and in young adults: a report of four cases with ultrastructural, immunohistochemical, and DNA flow cytometric analysis

Clear cell sarcoma of the kidney is a distinct, highly malignant pediatric neoplasm. Its occurrence in adults is extremely rare and the subject of isolated case reports. We present a series of four cases (three males and one female) identified in an adolescent and in young adults (16, 18, 20, and 25 years) with flank mass (three cases), hematuria (two cases), flank pain (two cases), and hypertension (one case). Three patients had stage III disease and one had stage I disease (National Wilms' Tumor Study staging system). All tumors had predominantly or exclusively the classic histology of a monotonous proliferation of uniform small round cells with evenly distributed fine chromatin, although focal microcyst formation (two cases) and spindled architecture (one case) (variant patterns) were also noted. Therapy in all cases consisted of surgery and chemotherapy with or without radiation. Follow-up data (29-202 months) showed distant metastases in all four cases, including the lung (four cases), bone (two cases), and the liver (two cases). Three patients died of disease at 29, 59, and 63 months (mean, 50.3 months), and one patient is alive with no evidence of disease at 202 months. Ultrastructural features included scattered primitive junctions, short and irregular cytoplasmic extensions, and scant to a moderate amount of mitochondria. Immunohistochemical study (three cases) showed immunoreactivity with vimentin (two cases) and no reaction with cytokeratin, epithelial membrane antigen, S-100 protein, or desmin. Flow cytometric analysis showed diploid DNA content in three primary tumors and tetraploidy in one metastatic tumor. The proliferative activity (S-phase fraction) was low to intermediate (mean, 9.8%). Our data suggest that clear cell sarcoma of the kidney in the young adult age group resembles its pediatric counterpart in ultrastructural and immunohistochemical characteristics, proclivity for skeletal and visceral metastasis, DNA diploid status with relatively low S-phase, and aggressive clinical course. Clear cell sarcoma of the kidney in adult patients, although rare, must be differentiated from sarcomatoid carcinoma, sarcomas, and round cell tumors because of its unique characteristics in comparison to other renal neoplasms.

Effect of various ions, pH, and osmotic pressure on oxidation of elemental sulfur by Thiobacillus thiooxidans

The oxidation of elemental sulfur by Thiobacillus thiooxidans was studied at pH 2.3, 4.5, and 7.0 in the presence of different concentrations of various anions (sulfate, phosphate, chloride, nitrate, and fluoride) and cations (potassium, sodium, lithium, rubidium, and cesium). The results agree with the expected response of this acidophilic bacterium to charge neutralization of colloids by ions, pH-dependent membrane permeability of ions, and osmotic pressure.

Glycogen-rich mesothelioma

A glycogen-rich epithelial mesothelioma is described. This variant is uncommon, but important to recognize since it is readily confused on routine light microscopy with other clear cell tumors involving the pleura. Ultrastructural and immunohistochemical studies can be helpful in establishing the correct diagnosis. Significant recent advances in the immunohistochemistry of epithelial mesothelioma are briefly reviewed.

Granular cell tumor: a review of the pathology and histogenesis

As the name suggests, the histogenesis of the granular cell tumor is uncertain, but this intriguing neoplasm has occasioned much speculation and controversy since its description in 1926 as a myoblastoma. Though ubiquitous in its anatomic location, it is usually small, solitary, benign, and readily recognized by routine light microscopy, and questions concerning it are principally academic. However, a small number of cases are malignant and they can be difficult to identify in paraffin sections. The combined input from immunohistochemistry and electron microscopy has greatly clarified understanding of the morphology of this lesion and both methods are helpful when the differential diagnosis is a problem. The cell of origin is still undecided, and although distinct neural features argue for Schwannian origin, the noncommittal term granular cell tumor continues to be appropriate.

Phase II trial of liposome-encapsulated doxorubicin, cyclophosphamide, and fluorouracil as first-line therapy in patients with metastatic breast cancer

PURPOSE

To determine the efficacy and safety profile, including the risk for cardiac toxicity, of liposome-encapsulated doxorubicin (TLC D-99), fluorouracil (5-FU), and cyclophosphamide as first-line chemotherapy in patients with metastatic breast cancer (MBC).

PATIENTS AND METHODS

Forty-one women were registered in this phase II study. All patients had measurable disease and no previous chemotherapy for MBC. Treatment consisted of TLC D-99 60 mg/m2 and cyclophosphamide 500 mg/m2 on day 1 and 5-FU 500 mg/m2 on days 1 and 8 every 3 weeks. Serial cardiac monitoring, including endomyocardial biopsies, was performed.

RESULTS

The overall response rate was 73% (95% confidence interval, 57% to 86%). The median duration of response was 11.2 months, the median time to treatment failure was 8.1 months, and the median overall survival duration was 19.4 months. The median number of cycles per patient was 10. The median cumulative dose of TLC D-99 was 528 mg/m2. Ten patients required hospitalization for febrile neutropenia. Nausea/vomiting, stomatitis, and fatigue higher than grade 2 occurred in 12%, 15%, and 41% of patients, respectively. Twenty-one patients reached a cumulative doxorubicin dose greater than 500 mg/m2. Three patients (7%) were withdrawn from the study due to protocol-defined cardiac toxicity, two because of a decrease in left ventricular ejection fraction to < or = 40%, and one because her endomyocardial biopsy result was grade 1.5. One patient had congestive heart failure that was probably nonanthracycline related.

CONCLUSION

This chemotherapy regimen, including TLC D-99, was highly active against MBC and associated with low cardiac toxicity despite high cumulative doses of doxorubicin.

Allelic losses at chromosome 8p21-23 are early and frequent events in the pathogenesis of lung cancer

Allelic losses on the short arm of chromosome 8 (8p) have been reported as frequent events in several cancers, including lung. However, no comprehensive mapping analysis of chromosome 8p in lung cancer tumors has been performed, and no data are available about the stage at which these abnormalities occur during the multistage development of lung cancer. Using 26 microsatellite markers, we mapped the chromosome 8 regions frequently deleted in lung cancer in 13 small cell carcinoma and 17 non-small cell lung carcinoma cell lines and in 68 microdissected archival primary lung tumors (22 small cell lung carcinomas, 25 squamous cell carcinomas, and 21 adenocarcinomas). We also studied the role of 8p deletions in lung cancer pathogenesis by examining 95 microdissected normal epithelium and preneoplastic samples from 11 surgically resected squamous cell lung carcinomas and from 58 bronchoscopy biopsy samples obtained from 31 current and former smokers. High frequencies of deletions at 8p21-23 regions were detected in lung cancer cell lines and in primary lung tumors. Deletions commenced early during the multistage development of lung cancer at the hyperplasia/metaplasia stage in cancer patients and in smokers without cancer. Allelic deletions persisted for up to 48 years after smoking cessation. There was a progressive increase of the overall 8p21-23 loss of heterozygosity frequency and in the size of the deleted region with increasing severity of histopathological preneoplastic changes. In epithelial samples from resected squamous cell lung carcinomas, we compared the presence of loss of heterozygosity at 8p21-23 with deletions at chromosomes 3p and 9p. Of interest, the pattern of deletions was not random, and 8p21-23 allelic losses always followed 3p deletions and usually followed 9p deletions. We conclude that 8p21-23 deletions are frequent and early events in the pathogenesis of lung carcinomas.

Alveolar adenoma: a histochemical, immunohistochemical, and ultrastructural analysis of 17 cases

Alveolar adenoma of lung is a rare benign neoplasm of uncertain histogenesis. Its rarity hampers characterization of its epithelial and mesenchymal elements. Clinical and histopathologic features of 17 alveolar adenomas were reviewed. Histochemistry was performed on 10 cases, ultrastructural analysis on two, and immunohistochemistry on six cases for pneumocyte markers, thyroid transcription factor (TTF-1), surfactant protein markers pro-SP-B and pro-SP-C, and the Clara cell marker, CC10. Immunohistochemistry was performed in nine cases for desmin, smooth muscle actin, muscle-specific actin, cytokeratin, proliferating cell nuclear antigen (PCNA), factor VIII, and carcinoembryonic antigen. The mean age was 53 years. Seven cases occurred in men, and nine occurred in women. The age and sex were not known for one patient. The tumors were coin lesions on chest radiographs in asymptomatic patients except for one (cough). The mean size was 2.2 cm. The tumors were well demarcated with multiple cystic spaces containing granular material. Mostly type 2 pneumocytes lined the cystic spaces with fewer type 1 cells and no Clara cells. This was confirmed by staining for TTF-1, pro-SP-B, and pro-SP-C and by ultrastructure. CC10 was negative in all cases. The stroma varied from prominent spindle cells with a myxoid matrix to thin alveolar septa. The interstitial spindle cells resembled fibroblasts by immunohistochemistry and ultrastructure. Follow-up data available in five cases showed no recurrence at 2, 2, 5, 8, and 13 years. In summary, alveolar adenoma is a benign neoplasm consisting of an intimate admixture of alveolar epithelial and septal mesenchymal tissue. Most of the epithelial cells are type 2 pneumocytes, and the interstitial stromal cells are fibroblasts or fibroblast-like cells. Recognition of its characteristic morphological appearance allows for its distinction from other benign lesions of the lung.

Deletions of chromosome 4 at multiple sites are frequent in malignant mesothelioma and small cell lung carcinoma

Recent allelotyping studies suggest that allelic losses at one or both arms of chromosome 4 are frequent in several tumor types. Cytogenetic studies of malignant mesothelioma (MM) and comparative genomic hybridization analyses of small cell lung carcinoma (SCLC) suggest that chromosome 4 deletions may also play a role in these tumor types, although these results have not been confirmed by allelotyping. In an effort to more precisely identify and map the locations of putative tumor suppressor gene(s) on chromosome 4 involved in the pathogenesis of these tumors, we performed loss of heterozygosity studies using 16 polymorphic microsatellite markers. After precise microdissection of archival surgical cases, we studied DNA obtained from 20 MMs, 21 SCLCs, and 20 non-SCLCs (NSCLCs). In addition, DNA from 14 SCLC and 17 NSCLC cell lines and corresponding B lymphoblastoid lines were studied. In MM and SCLC, we observed frequent losses at three nonoverlapping regions: (a) 4q33-34 (region R1; >80%); (b) 4q25-26 (region R2; >60%); and (c) 4p15.1-15.3 (region R3; >50%). Losses at these sites occurred at lower frequencies in NSCLC (>20-30%). Data from tumors and cell lines were similar. In MM and SCLC, the most frequently observed pattern was loss at all three regions. However, in NSCLC, the most frequent pattern was loss at R3 alone. Our study has delineated three nonoverlapping regions of frequent deletions on chromosome 4 in MM and SCLC, suggesting that there may be three putative suppressor genes on chromosome 4, the inactivation of which may be important in the pathogenesis of these tumor types.

Landmark discrimination learning in the dog

Allocentric spatial memory was studied in dogs of varying ages and sources using a landmark discrimination task. The primary goal of this study was to develop a protocol to test landmark discrimination learning in the dog. Using a modified version of a landmark test developed for use in monkeys, we successfully trained dogs to make a spatial discrimination on the basis of the position of a visual landmark relative to two identical discriminanda. Task performance decreased, however, as the distance between the landmark and the "discriminandum" was increased. A subgroup of these dogs was also tested on a delayed nonmatching to position spatial memory task (DNMP), which relies on egocentric spatial cues. These findings suggest that dogs can acquire both allocentric and egocentric spatial tasks. These data provide a useful tool for evaluating the ability of canines to use allocentric cues in spatial learning.

Electron microscopy in tumor diagnosis: indications for its use in the immunohistochemical era

The electron microscope reveals much more information on tumor cell structure than can be obtained with the light microscope, and some of the data are useful in diagnostic studies. In this review, major contributions of electron microscopy in the main tumor categories are discussed. To select between immunocytochemistry and electron microscopy, the probable contributions of each in the context of the particular case must be assessed. Usually, electron microscopy will only be requested after a battery of immunostaining procedures has been performed and found to be insufficient, but there are occasions when ulstrastructural study is logically the first choice after routine light microscopy. It is worth taking tissue for possible electron microscopy from any tumor that is known or anticipated to be a diagnostic problem.

Alveolar soft-part sarcoma: a review of the pathology and histogenesis

The descriptive designation, alveolar soft-part sarcoma, continues to be used for this uncommon soft-tissue malignancy because an acceptable hypothesis for its histogenesis has not been advanced, despite studies with electron microscopy and immunohistochemistry. These techniques have, nevertheless, provided significant information that is useful in the differential diagnosis of the tumor and pertinent in speculation concerning its nature. The most intriguing ultrastructural feature is the secretory process that culminates in the formation of the distinctive cytoplasmic crystals. Myogenic differentiation has been favored in a number of recent reports on the basis of immunohistochemical findings and the presence of the crystals does not rule out the possibility, but accounts of immunoreactivity for the myogenic regulatory protein MyoD1 have not been confirmed in subsequent studies or in the authors' own staining of six cases.

Epithelioid hemangioendothelioma of soft tissue: report of a case with ultrastructural observations

The ultrastructure of an epithelioid hemangioendothelioma arising in the soft tissues of the neck of an 18-year-old female is reported. Comparison with similar tumors in other sites from the authors' electron microscopy files indicates that diffuse nonspecific intermediate filaments, pinocytotic vesicles, intracytoplasmic lumens, and pericytic cells are frequent but variable features of this neoplasm.

Small cell undifferentiated carcinoma of the pancreas

Small cell undifferentiated carcinoma of the pancreas is a rare neoplasm: Only 12 cases have previously been documented. This paper describes the clinical evolution, immunohistochemical profile, and ultrastructural features of a case occurring in a 37-year-old woman.

Solid and papillary tumor of the pancreas: ultrastructural observations on two contrasting cases

Two papillary and solid tumors of the pancreas are reported which differed in their clinical features, ultrastructure, and biologic behavior. Both tumors contained papillary and solid areas by light microscopy. One tumor followed the more usual indolent course. The second patient presented with a liver metastasis and died of progressive disease in a relatively short period of time. Neither neoplasm showed convincing immunohistochemical or ultrastructural evidence of endocrine differentiation, but the electron microscopic findings hinted that this tumor possesses at least latent endocrine properties.

Endocrine carcinoma of the kidney

A 4-cm mass in the right kidney of a 43-year-old female had an endocrine appearance by light microscopy and electron microscopy confirmed this impression, demonstrating the presence of numerous cytoplasmic granules of endocrine caliber. Unusual features were patchy immunoreactivity for chromogranin, and polarity of the granules within the neoplastic cells. Extrarenal extension and liver metastasis were documented.

Neuroendocrine tumors of the lung. Pathology and molecular biology

Our understanding of the molecular genetic changes in lung cancer pathogenesis is advancing rapidly with several specific genes and chromosomal regions having been identified. As the biochemical functions of the proteins encoded by these genes are discovered, they appear to fall into several growth regulatory pathways. The large number of genetic lesions in clinically evident lung cancer has prompted searching for mutations in preneoplastic lung tissue before the pathologic evidence of cancer as a tool for early molecular diagnosis. In addition, these markers need to be rigorously assessed for their prognostic importance. Finally, understanding the molecular basis of lung cancer should allow "translation" of these findings from the bench to the bedside. These include very early molecular diagnosis, identification of persons at highest risk of developing lung cancer to allow for more effective smoking cessation strategies, chemoprevention, and very early treatment studies (clinical studies beginning); rational development of novel therapies such as immunization against tumor-specific mutant peptides (clinical studies ongoing); blocking the expression of activated oncogenes (such as with antisense or triple helix agents); and replacing defective tumor suppressor genes (clinical studies ongoing).

Keratomycosis in a Percheron cross horse caused by Cladorrhinum bulbillosum

This report describes an infection of a horse's cornea caused by Cladorrhinum bulbillosum. Minor surgery and treatment with antibiotics successfully resolved the infection. The only previous reported case involving this fungus was an Argentinian boy who was infected while working with horses.

Clear-cell carcinoma: an ultrastructural study of 57 tumors from various sites

Clear-cell carcinoma is a convenient and frequently used descriptive term for a malignant epithelial neoplasm that is entirely or largely composed of cells with optically clear cytoplasm in hematoxylin-eosin-stained sections. Transmission electron microscopy was performed on 57 tumors from various sites to investigate the fine structural basis for the clarity of the cytoplasm. The clear appearance resulted from the presence of one or several of the following features, as the sole or predominant cause or in combination: glycogen, lipid droplets, mucin vacuoles or diffuse mucosubstances, dilated cisternae, swollen or unusually large mitochondria, large solitary membrane-limited vacuoles or numerous smaller vacuoles, intracytoplasmic lumens, expanded intercellular spaces, cytoplasmic pseudoinclusions, and a paucity of organelles. Degenerative changes contributed to the clear appearance by inducing swelling of mitochondria and creating lucent cytosol. The factors responsible for the clear cytoplasm were not always consistent with regard to tumor type or site of origin, but glycogen was the commonest reason among the 57 tumors studied and the principal cause in tumors of the female genital tract, skin, and salivary glands, while renal cell carcinomas tended to possess an admixture of glycogen and lipid droplets. Because of the heterogeneity of the subcellular changes that can produce optically clear cytoplasm, electron microscopy has a limited role in determining the primary site of a metastatic clear-cell carcinoma.

Ewing's sarcoma and peripheral primitive neuroectodermal tumor: an interim report

The primitive neuroectoderm and its progeny seemingly give rise to an ever-increasing number of clinicopathologic entities. Ewing's sarcoma and peripheral primitive neuroectodermal tumor have recently been united by relatively unique antigens expressed by the MIC-2 gene, commonly coexpressed neural markers, and cytogenetic and molecular genetic abnormalities. Because of these factors, the current thinking is that Ewing's sarcoma and the peripheral primitive neuroectodermal tumor are parts of a phenotypic spectrum. We present an "interim report" on this group of neoplasms, emphasizing their presentation in the head and neck.

Cellular schwannoma of the bronchus

A cellular schwannoma in a bronchus of a 64-year-old female is reported with immunocytochemical and ultrastructural observations. One previous case arising in the lung has been reported. The tumor formed a 3-cm exophytic mass in a segmental bronchus. Pneumonectomy was performed. The tumor was moderately cellular and devoid of Verocay bodies, and the spindle cells were immunoreactive for S-100 protein. Electron microscopy revealed schwannian features that were less developed than in a classic schwannoma.