Ancient neurilemmoma is a cellular form of ordinary neurilemmoma, showing nuclear polymorphism and hyperchromasia. The majority of these  lesions are benign.

Imaging features:

On plain CXR a paravertebral soft tissue mass is seen. There is often erosion of the adjacent rib and vertebral body, splaying of ribs may also be see.

Calcification in benign schwannomas is rare, it is seen with greater frequency in ancient neurilemmoma. If there is rib or vertebral destruction the lesion should be considered malignant.

CT is useful in defining the exact location of the mass and will better demonstrate adjacent bone involvement.Contrast enhancement will vary depending on tumor size and degree of necrosis

MR with contrast:

This is the preferred imaging modality. Multiplanar capabilities and soft tissue resolution will assist in evaluating the tumor, assessing craniocaudal extent and any extension into the spinal canal.

In large lesions enhancement will be heterogenous reflecting cystic degeneration and necrosis, homogenous enhancement is usual in small  lesions.