Impacts after inhalation of nano- and fine-sized titanium dioxide particles: morphological changes, translocation within the rat lung, and evaluation of particle deposition using the relative deposition index.

A 3-week inhalation study with nano- and fine-sized titanium dioxide (TiO(2)) with 3, 28, and 90 days recovery time was performed in female Wistar rats. Lung volume measurements, histology, electron microscopy, hematology, and bronchoalveolar lavage (BAL) fluid analyses were conducted and the relative deposition index (RDI) was calculated. Minimal inflammatory changes in the lungs, leucopenia, and a decrease in ß-glucuronidase were observed. Particles were mainly deposited in alveolar macrophages and, to a lesser extent, in type-I pneumocytes, and this was quantified using the RDI. Rarely, particle-laden cells were observed inside capillaries. Therefore, minimal translocation of particles into the bloodstream has to be considered. Significant changes, e.g. in elicited effects or translocation behavior, between nano- and fine-particle-treated groups were not observed.

A biphasic malignant mesothelioma of the peritoneum and pleura in a horse.

This report describes the macroscopic, histologic, immunohistologic and ultrastructural characteristics ofa biphasic malignant mesothelioma in the peritoneal and pleural cavity of a 13-year-old Icelandic pony mare, which exhibited recurrent ascites clinically. Immunohistology was performed employing multiple monoclonal antibodies against cytokeratins (CK) and vimentin. The ultrastructural examination included the quantitative evaluation of the length to diameter ratio of the microvilli. Post mortem examination revealed a severe ascites and hydrothorax. The serosal surfaces of the peritoneum and pleura displayed poorly-demarcated, multifocal to coalescing laminar masses and small nodules. Histology revealed a bimorphic mass consisting of spindle-shaped cells and microcystic epithelioid areas. A transcoelomic and local invasive growth pattern as well as lymph node metastases were noticed. Immunohistology revealed a strong expression of CK. Though a low and moderate expression of CK5/6 and CK20 was present, respectively, CK7 and CK10-antigens were lacking. Ultrastructurally, the epithelioid mesothelioma cells displayed long microvilli, cytoplasmic tonofilaments, and desmosomes. Quantitative evaluation of the length to diameter ratio of the 10 longest microvilli revealed a mean value of approximately 16.2. Summarized, this report described the case of a malignant biphasic mesothelioma with an atypical CK20 expression but a characteristic ultrastructural morphology including long microvilli.

[Metastasizing epitheliotropic T-cell lymphoma (Mycosis fungoides) in two guinea pigs (Cavia porcellus)]. / Metastasierendes epitheliotropes T-Zell- Lymphom (Mycosis fungoides) bei zwei Meerschweinchen (Cavia porcellus).

Two guinea pigs (Cavia porcellus) were presented with a clinical history of a chronic, unresponsive skin disorder with scaling, itching and alopecia. After clinical differential diagnoses (e. g. ectoparasitosis, dermatomycosis, endocrinopathy or allergy) had been ruled out, a skin biopsy revealed an epitheliotropic lymphoma (Mycosis fungoides). The pathohistological examination of the skin showed focal intraepidermal accumulations of tumorous lymphocytes also known as pautrier microabscesses. A full necropsy displayed also metastases in lymph nodes, and additionally tumor cells within skeletal muscle, heart, lung, liver and kidney in one animal. Immunohistochemically, neoplastic cells were characterized by an expression of the T-cell receptor CD3. Generally epitheliotropic T-cell lymphomas are rare neoplasms of unknown cause and reports in guinea pigs are scarce. The most frequent neoplasms of the skin in this species are lipomas and trichofolliculomas. Initially a neoplasm was not suspected in both cases presented here. An epitheliotropic T-cell lymphoma should be considered as differential diagnosis in any case of unresponsive or recurrent scaling, itching and erythematous skin changes with alopecia, especially if the skin disorder is accompanied by weight loss and a poor general condition. In such cases the epitheliotropic T-cell lymphoma is easily diagnosed by using cutaneous biopsy samples. With those cutaneous biopsy samples the definitive diagnosis of an epitheliotropic lymphomas was made in both cases.

Spontaneously occurring multicentric basal cell carcinoma and keratoacanthomas in a multimammate mouse (Mastomys spp.).

A multicentric basal cell carcinoma was diagnosed in a male multimammate mouse (Mastomys spp.) with widespread cutaneous alterations. Macroscopically, the skin was thickened and extremely wrinkled. Histopathological examination showed multicentric expanding cell-rich tumors composed of basaloid cells interpreted as basal cell carcinoma. Immunohistochemistry detected strong cytokeratin 14 positivity in the epidermal basal layer and in loosely arranged areas of these tumors but only a minimal positive reaction in densely packed areas of tumor cells. Furthermore, samples from the abdomen showed 3 nodular proliferations diagnosed as keratoacanthomas.