Rhabdomyosarcoma of the pectoral muscles of a free-living European robin (Erithacus rubecula)

Abstract

An adult free-living European robin (Erithacus rubecula) with a large, firm, subcutaneous mass on the pectoral muscle was examined. The bird was unable to fly and died spontaneously. Necropsy revealed a yellowish, bilobate mass almost completely replacing the pectoral muscles with extensive osteolysis of the keel bone. Histopathology revealed a poorly demarcated, highly cellular sarcomatous tumour with metastases to the lungs, pulmonary blood vessels and heart. Immunohistochemistry was negative for neuron-specific enolase, S-100 protein and the p-27 major capsid protein of avian leukosis viruses. The homogeneously positive immunolabelling for vimentin and scattered positivity for myoglobin and desmin suggested a diagnosis of rhabdomyosarcoma. A retrospective examination of the records for 194 birds of the thrush family, including 64 robins submitted over a 20-year period, showed no diagnoses of neoplasia.

Description Of An Anaplastic Rhabdomyosarcoma In A Cockatiel (Nymphicus Hollandicus)

“…On the other hand, similar to our case, Fernandez-Bellon et al (2003) described comparable results concerning expression of actin and desmin biomarkers in an avian rhabdomyosarcoma [1]. The uneven expression of some specifi c biomarkers in avian rhabdomyosarcomas could be due to the degree of differentiation of the rhabdomyocytes [1,[9][10][11].…”

“…They described the tumour as composed of spindle cells with indistinct cell borders, marked anisocytosis and anisokaryosis, a high nuclear to cytoplasmic ratio, and a moderate amount of eosinophilic cytoplasm. Few multinucleated giant cells were also observed [11]. In another report, Fernández-Bellon et al (2003) mention a highly cellular, poorly demarcated, unencapsulated invasive sarcoma.…”

“…Concerning the α-smooth muscle actin, rare positive immunostaining is not surprising in rhabdomyosarcoma [9][10][11]. The biomarkers are variably expressed depending upon the grade of differentiation of neoplastic cells [10,11].…”

“…The biomarkers are variably expressed depending upon the grade of differentiation of neoplastic cells [10,11]. The uneven staining for actin could be due to the heterogeneity of neoplastic cells.…”

Retrobulbar rhabdomyosarcoma in a neotropical peregrine falcon (Falco peregrinus cassini)

“…Neoplasms of the retrobulbar region are usually differentiated by tissue origin and immunohistochemical staining, which is now the preferred method for differentiation and diagnosis of sarcomas and rhabdomyosarcomas . Immunopositive reactions to desmin are normally deterministic in the diagnosis of rhabdomyosarcomas; however, we had a negative reaction to desmin and a positive reaction to actin.…”