TITLE:
Adult Neuromuscular Choristoma in the Intraconal Region of the Orbital Muscle: A Case Report
AUTHORS:
Xuecheng Ge, Liangping Luo
KEYWORDS:
Neuromuscular Choristoma, Desmoid-Type Fibromatosis, Orbit, Case Report
JOURNAL NAME:
Journal of Biosciences and Medicines,
Vol.12 No.11,
November
13,
2024
ABSTRACT: Background: Neuromuscular choristoma is a rare benign peripheral neuropathy composed of ectopic mature muscle fibers and nerve bundles, usually involving large nerve roots or trunks, such as brachial plexus and sciatic nerve. NMC usually occurs in childhood, and some cases are congenital. Here, we report a case of adult orbital intraconal NMC. The resected specimens were fish-like and tough. Histological pathology suggested that the specimen was composed of mature skeletal muscle tissue interspersed with peripheral nerve bundles. Histopathological examination revealed that the left orbital mass was composed of mature skeletal muscle tissue interspersed with surrounding nerve fascicles. Immunohistochemistry: S-100 protein was positive. In general, postoperative histopathological examination ultimately determined the diagnosis of NMC in the intraconal region of the orbital muscle. Case Presentation: A 51-year-old female patient was admitted to the hospital due to periocular pain for 2 weeks. Orbital CT scan showed an irregular soft tissue density in the left orbital muscle cone area, and the boundary between the local and the left lateral rectus muscle was unclear. Magnetic resonance imaging showed that there was an oval abnormal signal in the posterior lateral space of the left eyeball, with a clear edge and a size of about 22 mm × 8 mm. The boundary between the local area and the left lateral rectus muscle was unclear, and the optic nerve was compressed to the right side. The T1 WI showed low signal, T2-FS showed high and low mixed signal, and the enhanced scan showed continuous obvious enhancement. Eventually, the patient underwent surgical resection of the lesion. Conclusions: NMC is a rare benign peripheral neuropathy, especially NMC in the orbital muscle cone. There is no specificity in clinical and imaging examinations. Accurate diagnosis before surgical resection is very challenging for clinicians and radiologists. Importantly, we can differentiate orbital NMC from other types of orbital tumors.