Age / Sex : 33 / F

Chief complaint: Left posterior neck, shoulder pain (O: 1year ago)

1) What is your impression?

Two weeks later, you can see the final diagnosis with a brief discussion of this case.

(Quiz는 quiz일 뿐이오니 답안은 한개만 보내주시기 바라오며, 복수의 답안을 보내주시는 분은 정답이 포함되어 있더라도 부득이 semi-correct answer로 처리토록 하겠습니다.)

Courtesy: 홍석주(Suk-Joo Hong), 고려대 구로병원(Korea University Guro Hospital)

Malignant peripheral nerve sheath tumor

Discussion

Findings:

Elongated soft tissue mass lesion in left neural foramen of C7/T1, extending from intradural space to extraforaminal level along existing C8 nerve root.

. Soft tissue mass size was about 2.2 cm long, 1.4 x 1 cm in transverse diameter.

. Mass shows homogeneous T1 iso, T2 slightly high signal intensity to spinal cord, with diffuse well enhancement pattern.

. Neural foraminal widening with posterior pressure erosion of C7 left posterolateral body is seen, with relatively well defined margin of the mass.

. Left C8 root is centrally located in the entire length of the mass lesion.

. This mass lesion is somewhat increased in volume and size since 2013-01-21 C-spine MRI.

Differential Diagnosis: Neurofibroma more likely than schwanoma

Diagnosis:  Malignant peripheral nerve sheath tumor

Discussion:

Malignant peripheral nerve sheath tumor

. Spindle cell sarcoma arising from nerve or neurofibroma or demonstrating nerve tissue differentiation

. 5-10% of all soft-tissue sarcomas, 5-year survival 43.7%

. Usually affect adult (20~50 years) without sex difference

. Associated with NF1 in 25-70% of cases

- Occurs a decade earlier, male predilection

. Located in deep soft tissues

- Commonly originated from the sciatic nerve, brachial plexus nerve, sacral plexus

- Skeleton, vertebral canal, lung, mediastinum, abdomen, peritoneum, heart and breast

Image findings

. MRI

- T1WI: usually low to iso signal intensity to muscle

- T2WI: high signal intensity

. Size: usually very big

. Indistinct boundary

. Inhomogeneous enhancement

. Abundant blood supply → clustered vessel signals

. Edema or invasion of surrounding soft tissue

. Connection with spinal nerve

- Inside or near and grows invasively along the nerve stem

- Connect with big or medium-sized nerve

. Enlarged intervertebral foramen

. Bone destruction

- Osteolytic bone erosion → distinguish them from benign

- Expansive change

. Usually does not involve the intervertebral disc

MRI features in the diffentiation of MPNST

. Large tumor size

. Heterogeneity on T1-weighted image

. Peripheral enhancement present

. Perilesional edema

. Intratumoral cystic change

             - Presence of two to four of those features is suggestive of malignancy

(specificity, 90%; sensitivity, 61%)

Findings summary

. Enlarged neural foramen, tumor connects with nerve root

. Large mass, inhomogeneous signal or density, necrotic focus or abundant blood supply in the center, inhomogenous enhancement, edema or invasion of surrounding soft tissue

. Extensive and obvious destruction of surrounding bones

Current case findings

.Benign looking imaging findings mimicking neurofibroma or schwanoma, except interval growth of mass size

References:

. Ning Lang, et al. Malignant peripheral nerve sheath tumor in spine: imaging manifestations. Clinical Imaging 36 (2012) 209–215.

. Mark D. Murphey, et al. Imaging of Musculoskeletal Neurogenic Tumors: Radiologic-Pathologic Correlation. Radiographics 1999;19:1253-1280.

. Junji Wasa, et al. MRI Features in the Differentiation of Malignant Peripheral Nerve Sheath Tumors and Neurofibromas. AJR 2010; 194:1568–1574.

. Chao-Shiang Li, et al. Differentiation of soft tissue benign and malignant peripheral nerve sheath tumors with magnetic resonance imaging. Clinical Imaging 32 (2008) 121 – 127.