The World Health Organization characterizes human choroid plexus tumor (CPT) as papilloma (CPP), atypical CPP (ACPP), and carcinoma (CPC). CPCs can disseminate via cerebrospinal fluid and be mistaken for metastatic carcinoma, creating a diagnostic challenge. Kir7.1 immunohistochemistry (IHC) is a highly reliable tool for diagnostic confirmation of CPTs and their differentiation from metastatic carcinomas in human beings and dogs. This study describes the neuropathology, Kir7.1 staining profile, and the immune cell population within the tumor microenvironment in 11 CPTs in dogs. Archived tissue sections with a diagnosis of CPT were examined and immunolabelled with Kir7.1 for diagnostic confirmation. The number of Ki67-positive neoplastic cells was calculated in 2.4 mm 2 (equivalent to 10 FN22/40X fields), and a mean value was generated for each neoplasm. IHC for CD3, CD20, MAC387, and Iba1 was performed for immune cell characterization, and the number of stained cells for each antibody was counted in 2.4 mm 2 , generating individual cumulative values for each antibody. T -tests with Bonferroni correction evaluated IHC differences between tumor types, and Spearman's rank correlations evaluated relationships among IHC markers. Kir7.1 immunoreactivity was intense at the apical cell membrane in CPPs and ACPPs, and at the apical cell membrane and cytoplasm in CPCs. Ki67 immunoreactivity was detected in all cases. CD3+ and CD20+ lymphocytes trended together ( p = 0.005) and were present within and around all CPTs. Five cases had intravascular MAC387+ monocytes. Iba1 immunoreactivity was robust within and around all tumors. Statistical differences in immune cell markers were not found among tumor types. As previously reported, Kir7.1 is a reliable antibody for the diagnosis of canine CPTs. Although immune cells were present in all cases, no significant associations were found between the type of cells and tumor diagnosis. The characterization of the immune cells within CPTs could be useful in future studies involving immunotherapy.

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Multiple myeloma oncogene 1/interferon regulatory factor 4 (MUM1/IRF-4) immunohistochemistry (IHC) is mainly used for diagnostic confirmation of plasma cell tumors (PCTs) in dogs and cats. This article describes MUM1/IRF-4 IHC expression in 20 cases of canine cutaneous histiocytoma (CH) and compares it with 10 cutaneous or mucocutaneous PCTs and 5 cutaneous histiocytic sarcomas (HSs) submitted to the same IHC protocol. All histiocytomas had strong nuclear and variable cytoplasmic immunolabeling for MUM1/IRF-4, whereas all PCTs had strong nuclear and moderate cytoplasmic immunolabeling for MUM1/IRF-4. No MUM1/IRF-4 immunolabeling was detected in the HSs. Although not typically a diagnostic challenge, MUM1/IRF-4 expression may have to be used with caution or in conjunction with additional immunomarkers to differentiate among poorly differentiated round cell tumors, especially when a histiocytic or plasma cell origin is suspected.

Juvenile Atlantic cod Gadus morhua (initial weight = 24.1 ± 1.4 g [mean ± SE) were fed diets in which fish meal (FM) was replaced with soy protein concentrate (SPC) and soybean meal (SBM) in isonitrogenous, isocaloric diets for 84 d. A standard marine finfish diet (3 mm, 54% protein, 14% fat) was modified to produce four experimental diets in which 50% of FM was replaced with soy at 0:1, 1:1, or 1:2 ratios of SPC:SBM and 100% FM replacement with a 1:1 ratio of SPC:SBM. No differences in mortality or feed intake were detected among treatments, and fish fed the 50% FM replacement diets, in any combination, grew as well or better than the control for all variables investigated. Cod fed the 100% FM replacement diet exhibited the lowest growth and differed from the control with respect to final body weight, growth, specific growth rate, and thermal‐unit growth coefficient. No enteritis was observed in histological sections. These results indicate that 100% fish meal replacement is not recommended, but 50% replacement can be used without significant reductions in growth or condition indices.