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Case Reports
. 2024 Jul;10(4):e1534.
doi: 10.1002/vms3.1534.

Fetal rhabdomyoma in a Thoroughbred filly

Giulia Rapezzano  1 , Alastair Foote  2 , Filippo Petrini  1 , Regina Pereira  1 , Marco Marcatili  1
Affiliations
Case Reports

Fetal rhabdomyoma in a Thoroughbred filly

Giulia Rapezzano et al. Vet Med Sci. 2024 Jul.

Abstract

A newborn Thoroughbred filly presented with a large mass located on the ventro-rostral aspect of the mandible. The mass was surgically removed under general anaesthesia. Upon gross examination, the mass was well circumscribed with a heterogeneous lobulated appearance. The results of histopathology and immunohistochemistry were consistent with a diagnosis of congenital fetal rhabdomyoma. On follow-up at six months post-surgical excision, no abnormalities were noted on clinical examination.

Keywords: equine; histopathology; horse; neoplasia; rhabdomyoma.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

FIGURE 1
FIGURE 1
Picture showing the ulcerated mass on the ventro‐rostral aspect of the mandible.
FIGURE 2
FIGURE 2
Gross appearance of the mass following surgical removal.
FIGURE 3
FIGURE 3
Photomicrograph of the cellular pattern within the rhabdomyoma, with irregular streams and small fascicles of spindle cells, as well as occasional elongated strap cells and multinucleate cells (A, B). Mitotically active cells are detected (black arrows, B). PTAH staining highlights cytoplasmic striation in some of the larger strap cells (white arrows, C). Infrequently, small localised areas of mineralisation are apparent in the stroma (D). A–C: H&E staining; D: PTAH. Scale bars: A = 200 µm, B = 100 µm C = 50 µm, D = 0.5 mm.
FIGURE 4
FIGURE 4
Immunohistochemical staining of serial sections of the tumour (A, H&E staining for comparison) demonstrated strong expression of desmin (B), moderate to strong smooth muscle actin (SMA) expression (C) and a smaller proportion of cells demonstrated variable nuclear expression of myogenin (D). Scale bars: A–D = 1 mm.
See this image and copyright information in PMC

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