Homozygous Pelger-Huet anomaly in three different crossbred rabbits: a case report

In this case report, three different crossbreedings of pet rabbits were performed producing affected as well as healthy bunnies. All affected rabbits were smaller and had local alopecia, exophthalmus, and limb deviations compared to their healthy littermates; thus, a homozygous form of Pelger-Huet anomaly was suspected. This anomaly was confirmed by blood examination in which granulocytes with oval nuclei and a very coarse chromatin pattern, as well as lymphocytes with micronuclei were noticed. Karyotype analyses of the lymphocytes revealed many chromosomal aberrations in affected rabbits. Moreover, severe arterial abnormalities in the pelvic cavity and proximal part of the pelvic limbs were also found in these rabbits. Our findings suggest a multigenic origin of Pelger-Huet anomaly in rabbits, because only male and female offspring with the otter colour of fur were severely affected by this congenital disorder.  

Thyroid follicular adenomas may display features of follicular carcinoma and follicular variant of papillary carcinoma

Thyroid follicular adenomas (FA) are encapsulated tumors lacking vascular, capsular or lymphatic invasion and the typical nuclear features of papillary carcinoma (PC). However, some FA demonstrate nuclear atypia reminiscent of either follicular carcinomas (FC) or follicular variant of papillary carcinomas (FVPC), suggesting they may represent precursors of malignant transformation. We hypothesized that an objective evaluation of nuclear chromatin patterns could be used to define atypical follicular tumors (AFT) that are likely to be premalignant. To test this hypothesis, we used a computer-aided image analysis system to define the chromatin pattern of nuclei from thyroid tumors. To validate the system, we analyzed 3000 nuclei from 10 FA, 10 FC, and 10 FVPC samples and accurately distinguished between these classes of tumors. Then, we analyzed nine AFT and, in parallel, we analyzed the tumors for activating mutations of N2-RAS and over-expression of RET. The predominant chromatin pattern of AFT was of FA type in two cases, FC type in two cases, and PC type in three cases. One case contained similar numbers of FC and PC nuclei and one was comprised of a mixture of the three nuclear types. Neither RAS mutation nor RET overexpression were detected in FA. N2-RAS mutations were found in 33% of AFT, 20% of FC and 20% of FVPC without correlation with chromatin pattern. Over-expression of RET was detected in 45% of AFT, 20% of FC and 50% of FVPC and was correlated with PC nuclei. These results show that AFT are a heterogenous group of tumors, containing genuine benign tumors and tumors that share morphological and molecular features with follicular and papillary carcinomas that might be precursors of both types of thyroid carcinomas.

Pilocytic Astrocytoma in a Cat

A 12-year-old crossbred female cat was presented for necropsy with a history of anorexia, ataxia, convulsions, and blindness. Grossly, a whitish, firm, and well-circumscribed nodule with an irregular surface of approximately 1.5 cm in diameter was observed in the right dorsal, parietal, and occipital lobes of the brain. Histologically, the tumor was composed of neoplastic astrocytes forming irregular interweaving sheets and bundles. These cells were elongated, spindle-shaped, and bipolar, and some had clear cytoplasm and a dense nuclear chromatin pattern. Extensive areas of cartilaginous and osseous metaplasia were observed. By immunohistochemistry, the neoplastic cells were found to be markedly positive for S-100 protein and glial fibrillary acidic protein. On the basis of morphologic and immunohistochemical features, the diagnosis of pilocytic astrocytoma was made.