Characterization of natural occurring Pneumocystis carinii pneumonia in pigs by histopathology, electron microscopy, in situ hybridization and PCR amplification

Macroscopic. histolog ic . ultrastruc tural. microbiologic. ill sirll hybridi za ti on (ISH ) and PCR detection results in three 8-week-old pi gs naturall y infected with Pllel.llllonsris c{lrinii (PC) are described . All an imals had a nonsu ppurati ve interstitial pneumoni a and intra-alveolar PlleulIlucysris organisms with foamy eos in ophili c and PAS positi ve appearance . Ultrastructurally. PC trophozoites and cysts we re observed in pigs No.2 and NO .3. with the fo rmer being much more numerous. PC organisms we re located on the alveolar surface or within the alveolar septa . Trophozoites had numerous filopodia and were thin-wall ed. Cysts had no o r few filopodia. we re thick- wa ll ed and co nt a ined intracysti c bodies. Using non-isotopic ISH on formalinfixed. paraffin-embedded lung tissue sections. PC DNA from pigs No.2 and No . 3 hyb ridi zed with a probe specific for PC ribosomal RNA (rRNA). Using primers spec ific for mit oc ho ndrial rRNA ge ne (pA Z I0 2- E/pAZ I 02-H). and for the interna l transcriber space rs of ribosomal gene of PC. PCR methods amplified a product in the lung of pigs No.2 and No.3 using either frozen or formalin -fi xed and paraffin -embedded lung tissue. DNA from Pig No. I samples did not amplify with any primer. This is the first time that molecular biology techniques (ill siru hybridi zation and PCR) have been applied to the study of porc ine pneumocystosis

Proposal of a 2-Tier Histologic Grading System for Canine Cutaneous Mast Cell Tumors to More Accurately Predict Biological Behavior

Currently, prognostic and therapeutic determinations for canine cutaneous mast cell tumors (MCTs) are primarily based on histologic grade. However, the use of different grading systems by veterinary pathologists and institutional modifications make the prognostic value of histologic grading highly questionable. To evaluate the consistency of microscopic grading among veterinary pathologists and the prognostic significance of the Patnaik grading system, 95 cutaneous MCTs from 95 dogs were graded in a blinded study by 28 veterinary pathologists from 16 institutions. Concordance among veterinary pathologists was 75% for the diagnosis of grade 3 MCTs and less than 64% for the diagnosis of grade 1 and 2 MCTs. To improve concordance among pathologists and to provide better prognostic significance, a 2-tier histologic grading system was devised. The diagnosis of high-grade MCTs is based on the presence of any one of the following criteria: at least 7 mitotic figures in 10 high-power fields (hpf); at least 3 multinucleated (3 or more nuclei) cells in 10 hpf; at least 3 bizarre nuclei in 10 hpf; karyomegaly (ie, nuclear diameters of at least 10% of neoplastic cells vary by at least two-fold). Fields with the highest mitotic activity or with the highest degree of anisokaryosis were selected to assess the different parameters. According to the novel grading system, high-grade MCTs were significantly associated with shorter time to metastasis or new tumor development, and with shorter survival time. The median survival time was less than 4 months for high-grade MCTs but more than 2 years for low-grade MCTs

Recommended Guidelines for Submission, Trimming, Margin Evaluation, and Reporting of Tumor Biopsy Specimens in Veterinary Surgical Pathology

eoplastic diseases are typically diagnosed by biopsy and histopathological evaluation. The pathology report is key in determining prognosis, therapeutic decisions, and overall case management and therefore requires diagnostic accuracy, completeness, and clarity. Successful management relies on collaboration between clinical veterinarians, oncologists, and pathologists. To date there has been no standardized approach or guideline for the submission, trimming, margin evaluation, or reporting of neoplastic biopsy specimens in veterinary medicine. To address this issue, a committee consisting of veterinary pathologists and oncologists was established under the auspices of the American College of Veterinary Pathologists Oncology Committee. These consensus guidelines were subsequently reviewed and endorsed by a large international group of veterinary pathologists. These recommended guidelines are not mandated but rather exist to help clinicians and veterinary pathologists optimally handle neoplastic biopsy samples. Many of these guidelines represent the collective experience of the committee members and consensus group when assessing neoplastic lesions from veterinary patients but have not met the rigors of definitive scientific study and investigation. These questions of technique, analysis, and evaluation should be put through formal scrutiny in rigorous clinical studies in the near future so that more definitive guidelines can be derived