Nerve Fiber Immunohistochemical Panel Discriminates between Nerve Sheath and Perivascular Wall Tumors.

Benign and malignant nerve sheath tumors (NST) pose a major challenge in routine diagnostic anatomic pathology because of shared histomorphological features with other soft-tissue tumors (STT). As a result, NST are often diagnosed as STT, a broad category that encompasses various entities including perivascular wall tumors (PWT) and that represents approximately 15% of all skin tumors in dogs. Immunohistochemistry (IHC) can assist the identification of histologic subtypes of STT. This IHC pilot study applies various markers largely expressed by peripheral nerves to twelve benign and six malignant NST and determines the intratumoral protein expression of laminin, periaxin-1, Sox-10 and S-100 in the NST subtypes. Furthermore, this study assesses the usefulness of peripheral nerve markers applied to diagnostic work cases and demonstrates the relevance of laminin expression patterns, periaxin-1 and Sox-10 in assisting the differentiation of NST from other STT, in particular from PWT.

Growth Factors and COX2 Expression in Canine Perivascular Wall Tumors.

Canine perivascular wall tumors (PWTs) are a group of subcutaneous soft tissue sarcomas developing from vascular mural cells. Mural cells are involved in angiogenesis through a complex crosstalk with endothelial cells mediated by several growth factors and their receptors. The evaluation of their expression may have relevance since they may represent a therapeutic target in the control of canine PWTs. The expression of vascular endothelial growth factor (VEGF) and receptors VEGFR-I/II, basic fibroblast growth factor (bFGF) and receptor Flg, platelet-derived growth factor B (PDGFB) and receptor PDGFRß, transforming growth factor ß1 (TGFß1) and receptors TGFßR-I/II, and cyclooxygenase 2 (COX2) was evaluated on frozen sections of 40 PWTs by immunohistochemistry and semiquantitatively scored to identify their potential role in PWT development. Statistical analysis was performed to analyze possible correlations between Ki67 labeling index and the expression of each molecule. Proteins of the VEGF-, PDGFB-, and bFGF-mediated pathways were highly expressed in 27 (67.5%), 30 (75%), and 19 (47.5%) of 40 PWTs, respectively. Proteins of the TGFß1- and COX2-mediated pathways were highly expressed in 4 (10%) and 14 (35%) of 40 cases. Statistical analysis identified an association between VEGF and VEGFR-I/II (P = .015 and .003, respectively), bFGF and Flg (P = .038), bFGF and PDGFRß (P = .003), and between TGFß1 and COX2 (P = .006). These findings were consistent with the mechanisms that have been reported to play a role in angiogenesis and in tumor development. No association with Ki67 labeling index was found. VEGF-, PDGFB-, and bFGF-mediated pathways seem to have a key role in PWT development and growth. Blockade of tyrosine kinase receptors after surgery could represent a promising therapy with the aim to reduce the PWT relapse rate and prolong the time to relapse.

Hemangiopericytoma in a female dog with direct invasion of abdominal cavity and pulmonary metastasis / Hemangiopericitoma em uma cadela com invasão direta da cavidade abdominal e metástase pulmonar

An intact adult female Poodle dog was presented with a history of an increase in volume in the left and right mammary inguinal glands. The histopathological examination revealed a proliferation of spindle cells arranged in bundles with concentric arrangements surrounding blood vessels, occasionally collapsed. Three weeks after the surgery, the animal presented a recurrence of the tumor that extended from the left inguinal mammary gland to the vulva. Necropsy revealed direct invasion of the abdominal cavity by the tumor and pulmonary metastasis. The definitive diagnosis of hemangiopericytoma was made by histopathological and immunohistochemical examination. Pulmonary metastasis of CHP (canine hemangiopericytoma) is rare and there is no previous report of direct invasion to the abdominal cavity as observed in the present case.

Uma cadela adulta, intacta, da raça Poodle, apresentou histórico de aumento de volume na mama inguinal direita. O exame histopatológico revelou proliferação de células fusiformes dispostas em bandas e arranjos concêntricos ao redor de vasos, os quais se apresentavam ocasionalmente colapsados. Três semanas após a cirurgia, o animal apresentou recorrência do tumor que se estendia até a vulva. No exame necroscópico, observou-se que a massa invadia a cavidade abdominal e presença de metástase no pulmão. O diagnóstico definitivo de hemangiopericitoma foi realizado por meio dos exames histopatológico e imuno-histoquímico. A metástase pulmonar do hemangiopericitoma canino é rara e não há relatos prévios de invasão direta para cavidade abdominal, como observado no presente caso.