Cutaneous Rhabdoid Tumor in a Cat

Abstract

Abstract. Rhabdoid tumor is a highly aggressive neoplasm of unknown cellular origin in humans, usually occurring in the kidney and central nervous system of infants or children. In older patients, it occurs rarely in other organs, including the skin and soft tissues. A subcutaneous mass in a 13-year-old male mixed-breed cat was composed of nests or sheets of round to polygonal cells with glassy eosinophilic cytoplasmic inclusions. Immunohistochemically, many neoplastic cells expressed vimentin, localized to the cytoplasmic inclusions, whereas the cytoplasm of some neoplastic cells was diffusely positive for neuron-specific enolase, neurofilament, or S-100 protein. By electron microscopy, the cytoplasmic inclusions were found to be composed of aggregates of intermediate filaments. These findings are quite similar to the histologic, immunohistochemical, and ultrastructural features of human rhabdoid tumors and the few rhabdoid tumors reported in animals.

Cutaneous extrarenal rhabdoid tumor in a dog: a case report

“…However, despite its morphological similarity under the light microscope, it soon became apparent that the immunohistochemical, ultrastructural and clinicopathological features differed between rhabdoid and Wilms' tumours (Haas et al 1981;Weeks et al 1989). According to previous reports (Izawa et al 2008), both renal and extrarenal RTs showed a similar histomorphological appearance including nests or non-cohesive sheets of round to polygonal cells with pale circular regions outlined by a eo- The histological findings of RT in skin were described to be very similar, but the immunochemical reactivity was variable, with the exception of a strong positive immunoreaction for vimentin (Fanburg-Smith et al 1998;Petitt et al 2005;Izawa et al 2008). Consideration of another case prompted the suggestion that epithelioid cell morphology along with positive immunohistochemical staining for vimentin, desmin, CD56, CD10, and WT-1 support an underlying poorly differentiated rhabdomyosarcoma (Petitt et al 2005).…”

“…Consideration of another case prompted the suggestion that epithelioid cell morphology along with positive immunohistochemical staining for vimentin, desmin, CD56, CD10, and WT-1 support an underlying poorly differentiated rhabdomyosarcoma (Petitt et al 2005). However, another study reported that immunopositivity for vimentin, neuron-specific enolase, neurofilament, and S-100 protein may suggest a neuroectodermal origin for the tumour (Izawa et al 2008). In the present study, pronounced immunoreactions were noted for vimentin and desmin, but not for other specific markers such as for the neuronal lineage (GFAP, S100), myogenic lineage (α-SMA, MyoD1), epithelial lineage (pancytokeratin), inflammatory cells (CD45, CD68) and melanocytes (HMB45).…”

“…Most cases of RT in veterinary medicine exhibited similar histopathological features to those of human RT. However, in contrast to human cases, most of these RT cases occurred in adults and extrarenal RTs, such as those of the gastric wall (Schauer et al 1994), brain (Steele et al 1997), orbit (Hong et al 1999) and skin (Izawa et al 2008), were more frequently reported than renal RTs.…”

“…Primary presentation in the skin is exceedingly rare and to the best of our knowledge, only two cases of extrarenal RT were reported in a dog (Chung and Do 2009) and a cat (Izawa et al 2008). Furthermore, prognosis differs markedly in cutaneous RTs compared to extrarenal RTs from other locations.…”

“…Histologically, RTs are characterised by sheets of highly pleomorphic "rhabdoid" cells which resemble rhabdomyosarcoma under the light microscope and which rely on the presence of large epithelioid cells with eccentric eosinophilic cytoplasm, vesicular nuclei, and prominent nucleoli (Petitt et al 2005;Izawa et al 2008). In contrast to rhabdomyosarcoma, RT cells often possess eosinophilic, globular/ fibrillar paranuclear inclusions and show various amounts of reactivity to lineage specific-immunohistochemical markers such as those targeted at mesenchymal cells, smooth muscle, skeletal muscle, melanocytes, epithelial cells and nerves (Fanburg-Smith et al 1998;Morgan et al 2000).…”