Participation of Tumor-Associated Myeloid Cells in Progression of Amelanotic Melanoma (RMM Tumor Line) in F344 Rats, with Particular Reference to MHC Class II- and CD163-Expressing Cells.

Tumor progression is often influenced by infiltration of myeloid cells; depending on the M1- or M2-like activation status, these cells may have either inhibitory or promoting effects on tumor growth. We investigated the properties of tumor-associated myeloid cells in a previously established homotransplantable amelanotic melanoma (RMM tumor line) in F344 rats. RMM tumor nodules were allowed to reach the sizes of 0.5, 1, 2 and 3 cm, respectively. Immunohistochemistry and flow cytometry was performed for macrophage markers CD68 and CD163, and for the antigen-presenting cell marker, MHC class II. Although no significant change was observed in the number of CD68+ and CD163+ macrophages during RMM progression, the number of MHC class II+ antigen-presenting cells was reduced in 3 cm nodules. Real-time RT-PCR of laser microdissection samples obtained from RMM regions rich in MHC class II+ cells demonstrated high expressions of M1-like factors: IFN-γ, GM-CSF and IL-12a. Furthermore, fluorescence-activated cell sorting, followed by real-time RT-PCR for CD11b+ MHC class II+ (myeloid antigen-presenting cells), CD11b+ CD163+ (M2 type myeloid cells), CD11b+ CD80+ (M1 type myeloid cells) and CD11b+ CD11c+ (dendritic cells) cells was performed. Based on the levels of inflammation- and tumor progression-related factors, MHC class II+ antigen-presenting cells showed polarization towards M1, while CD163+ macrophages, towards M2. CD80+ and CD11c+ myeloid cells did not show clear functional polarization. Our results provide novel information on tumor-associated myeloid cells in amelanotic melanoma, and may become useful in further research on melanoma immunity.

Myoepithelioma of the gland of the third eyelid in a dog.

A 12-year-old female miniature dachshund was presented with a tan-white, firm mass (4 × 3 × 2 cm) occupying the left medial canthus. The mass compressed and displaced the left eye dorsally, and it was surgically removed. Microscopically, the mass was composed of interlacing bundles of spindle cells with clear cytoplasm and a small number of atypical glandular epithelial cells. Immunohistochemically, the spindle cells expressed p63, α-smooth muscle actin and calponin, and were negative for cytokeratin AE1/AE3. The glandular epithelial cells expressed cytokeratin AE1/AE3. Based on these findings, this case was diagnosed as a myoepithelioma of the gland of the third eyelid.

Granulomatous Pneumocystis carinii pneumonia in patients with malignancy.

BACKGROUND: A review was undertaken of the clinical features and results of diagnostic tests in non-HIV infected patients who developed granulomatous Pneumocystis carinii pneumonia (PCP). METHODS: A retrospective review was performed of the charts and radiographs of patients with a granulomatous reaction to P carinii identified from computerised pathology records at Memorial Sloan Kettering Cancer Center, a university affiliated tertiary care hospital. RESULTS: Three cases were identified; the incidence of granulomatous PCP was 3%. All patients had risk factors for PCP and had received high dose corticosteroids which had been stopped. Two patients had received chemotherapy. Presentation was insidious with only mild symptoms; only one patient had fever. Chest radiographs showed a reticulonodular pattern. Bronchoscopy was negative for PCP in all cases and open lung biopsy was necessary. CONCLUSION: A granulomatous pathological reaction to PCP occurs rarely in patients with malignancy. In these cases the clinical presentation may be atypical and bronchoscopy can be non-diagnostic.

Pulmonary nodule due to Mycobacterium haemophilum in an immunocompetent host.

We present a case of a pulmonary nodular lesion in an immunocompetent patient documented at open lung biopsy to be due to Mycobacterium haemophilum. This organism has recently been recognized as a cause of disease in immunocompromised patients, presenting predominantly as skin lesions, arthritis, and rarely pneumonia. Because this mycobacterium is fastidious and difficult to grow without the use of special media and conditions, our case raises the possibility that M. haemophilum could be an underrecognized cause of granulomatous pulmonary lesions and should be considered particularly in cases where smears for acid-fast bacteria are positive but cultures are negative.