J Korean Soc Spine Surg.  2019 Sep;26(3):111-115. 10.4184/jkss.2019.26.3.111.

Paraspinal Ancient Schwannoma of the Dorsal Ramus Nerve: A Case Report

• Kim DG
• Jo YM

• KMID: 2459761
• DOI: http://doi.org/10.4184/jkss.2019.26.3.111

Abstract

STUDY DESIGN: Case report.
OBJECTIVES
We report a case of paraspinal ancient schwannoma located at the upper thoracic level that mimicked an atypical lipoma or complicated epidermoid cyst. SUMMARY OF LITERATURE REVIEW: Few case reports of paraspinal schwannoma have been reported and the incidence of ancient schwannoma in the paraspinal muscle layer is very rare.
MATERIALS AND METHODS
A 39-year-old man complained of a growing palpable back mass for 5 years. He experienced aggravated chronic discomfort around the mass while lying down. Both T1- and T2- weighted magnetic resonance imaging (MRI) showed a well-capsuled and heterogeneous high-signal mass in the muscle layer at the level from the T1 to T4 vertebral bodies on the right side of the midline. The tumor was completely removed by en bloc resection.
RESULTS
The pathologic examination revealed S-100 protein expression with degenerative changes. The lesion was diagnosed as an ancient schwannoma.
CONCLUSIONS
Schwannoma is one among the multiple possible causes of benign back masses. If a mass reveals a well-encapsulated heterogeneous mass on contrast MRI, a schwannoma should be suspected.

Keyword

Schwannoma; Back muscles

MeSH Terms

Adult
Back Muscles
Deception
Epidermal Cyst
Humans
Incidence
Lipoma
Magnetic Resonance Imaging
Neurilemmoma*
Paraspinal Muscles
S100 Proteins
S100 Proteins

Figure

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  Fig. 1. Magnetic resonance imaging showing (A) a well-defined, irregular thick-walled cystic lesion and (B) central non-enhancement with peripheral irregular heterogeneous enhancement.

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  Fig. 2. The excised mass. (A) The mass was solitary, well circumscribed, and capsulated. It presented yellow-to-gray coloration, myxoid and soft stromal areas, and multiple tan/brown hemorrhagic foci. (B) On a cut section, cystic changes were more evident.

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  Fig. 3. Microscopic images showing (A) a hypocellular area in the central region (white arrow) and a more cellular area in the peripheral region (black arrow), but less cellular than a typical schwannoma (hematoxylin and eosin [H&E], ×40). Both hyaline vascular changes (white arrow) and thrombi (black arrow) were present (H&E, ×100). (C) The typical Antoni A area was not identified; instead, only a vague Antoni A–like area was identified in this case (H&E, ×200). (D) Cellular features included bizarre nuclei (H&E, ×400).

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  Fig. 4. Immunohistochemistry revealed diffuse, high S-100 protein expression.

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