Sunday, 1 September 2019

Post traumatic Neuroma MRI

A 35 old male fell from 8 feet and experienced immediate spine and both hip pain with progressively worsening back pain that radiated to right hip and right lower extremity. Sharp pain radiated from back to toes, and experienced paresthesias from right knee to toes.
On examination, antalgic gait and unable to walk, weakness of right hip flexion, knee extension, ankle dorsiflexion and ankle plantar flexion. A straight leg raise test result was positive on the right at 15°, which indicated neuronal irritation, and was negative on the left leg.
MRI WHOLE SPINE show multiple level benign post-traumatic sub chondral collapses with marrow oedema. No obvious listhesis.
Study extended with MR Neurography of lumbosacral plexus shows a well-defined ovoid mixed but near cystic signal intensity lesion on right side of spine at lumbosacral junction deep to the right psoas muscle. Lesion is ovoid has typical teardrop shape with proximal portion tapering towards neural foramina suggestive of neural/perineural origin of lesion.
Considering history of trauma possibility of post-traumatic neuroma was suggested.

Histopathology examination : Neuroma.
Microscopy shows a disorganized fibroneural tissue contained randomly oriented nerve twigs surrounded by attenuated connective tissue and different types of cells like Schwann cells, macrophages, and fibroblasts, which may extend into adjacent adipose tissue.

Final diagnosis: Post traumatic Neuroma.

Post traumatic Neuromas (PTNs) of Lumbar Plexus

PTNs may be terminal occuring in amputation stumps or when the nerve is completely transected, or they may be in-continuity. Neuromas-in-continuity comprise most nerve injuries from laceration, contusion, or stretch injury.

A peripheral nerve MR Neurography an useful technique for the preoperative diagnosis, localization, and characterization of nerve abnormalities, including PTN formation.

Neuromas present as a fusiform mass with nerve continuity, may be similar in appearance to that of neurogenic tumors, such as schwannomas and neurofibromas. Neuromas unlike neurogenic tumors may not show enhancement. Unlike neurogenic tumors, neuromas-in-continuity lack a split fat sign, which represents a rim of fat that surrounds the tumor, particularly in relation to the proximal and distal portion of the nerve best appreciated on T1-weighted images. Neuromas-in-continuity also lack a target sign, which consists of high signal intensity in the periphery and low signal intensity in the central region of the lesion on T2-weighted images. PTNs of the peripheral nerves have been reported and tend to be low to isointense on T1-weighted imaging and hyperintense on T2-weighted imaging.

Lumbosacral PTN is relatively rare. Radiologists should be aware of the imaging appearance of injury-related neuromas for appropriate diagnosis and avoid misinterpretation as true neoplasms. 

1 comment:

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