Peer-reviewed veterinary case report
Injection site growths in 2 cats that looked like cancer but were not
By Godizzi, Francesco et al.·Published in Journal of veterinary diagnostic investigation : official publication of the American Association of Veterinary Laboratory Diagnosticians, Inc·2022·Department of Veterinary Medicine (DIMEVET), Italy·View original on PubMed →
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Original publication title: Extravascular papillary endothelial hyperplasia mimicking soft tissue sarcoma in 2 cats: a potential diagnostic pitfall.
- Species:
- cat
Plain-English summary
Two cats developed unusual lumps at their injection sites that were initially thought to be cancerous tumors. These lumps were later identified as a rare condition called papillary endothelial hyperplasia (PEH), which can mimic more serious issues like injection-site sarcoma. Fortunately, neither cat experienced any recurrence of the lesions after diagnosis. This case highlights the importance of accurate diagnosis to avoid unnecessary treatments for pets with similar symptoms.
People also search for: cat lump after injection · feline injection site sarcoma · cat soft tissue tumor diagnosis
Abstract
Papillary endothelial hyperplasia (PEH) is a rare soft tissue lesion arising from excessive reactive endothelial cell proliferation described in humans, dogs, and horses. PEH is considered a diagnostic challenge in humans, in which it is frequently misdiagnosed as angiosarcoma. We describe here PEH that developed at injection sites in 2 cats that were initially misdiagnosed as feline injection-site sarcoma by cytology and as subcutaneous angiosarcoma by histopathology. Morphologic features included sharp demarcation from surrounding tissues, and a layered microscopic architecture with an outer fibrous capsule from which emerged fibrovascular stalks covered by a monolayer of factor VIII-related antigen and CD31-positive flat-to-plump endothelial cells. Both lesions had a cystic core containing abundant erythrocytes and fibrin. PEH lesions did not recur in either case. Immunohistochemistry for α-smooth muscle actin and desmin demonstrated that the capsule was devoid of smooth muscle cells, excluding an intravascular origin. PEH in these cats was hypothesized to have developed extravascularly following trauma related to injection. We wish to provide awareness of PEH in domestic cats and of the risk of misdiagnoses leading to overtreatment.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/35168431/