Tissue from C5-C6 level extramedullary SOL, in a 20 year old male.
- Multiple discrete encapsulated nodules of schwann cells, with few serpentine growth pattern in a myxoid background.
- Many nodules show distinct Antoni A pattern with nuclear palisading and Verocay body.
- Peripheral rim of perineurial cells and a thin fibrous capsule are seen around nodules.
- Spindle cells show typically elongated wavy, buckled nuclei, and indistinct cytoplasmic borders, in a fibrillar eosinophilic background
- Atypical degenerative features are not seen here; however, should not be given importance in absence of mitoses and necrosis.
- Necrosis and mitotic activity are also not seen.
- Last image show single elongated neural structure, represent the remnants from spinal nerve.
Practical Points of Pathoclinics:
- Plexiform schwannoma is an uncommon type, representing just about 4-5% of all schwannomas.
- Plexiform schwannoma is usually a solitary lesion and common in dermis, subcutaneous and superficial soft tissues location, involving extremities and head and neck region. Deep-located tumors can be seen as well as uncommon sites like gastrointestinal tract. Deep-seated tumors may show necrosis and myxoid change.
- Plexiform schwannoma in spinal location is an extremely uncommon, only around approximately less than 10 cases are reported in Medline/PubMed database.
- Multiple Plexiform schwannomas are uncommon. It is rare to find an association with neurofibromatosis type 1 or 2. However, the presence of multiple lesions should be investigated for NF1 and NF2.
- Plexiform schwannoma has a circumscribed or infiltrative or serpentine growth pattern of multiple distinct nodules. Lymphoid aggregates can be seen in the tumor and capsule.
- Schwann cells are strong diffuse positivity for S100 protein. Perineurial cells occasional axons can be highlighted by EMA and neurofilaments stain.
- Pediatric age group plexiform cellular schwannoma shows diffuse cellularity without nuclear palisading and with occasional mitoses and almost no necrosis, which are in the past considered as a plexiform malignant peripheral nerve sheath tumor in a plexiform neurofibroma. These tumors have tendency for local recurrence but no metastatic potential. It has no association with NF1 or NF2.
- Management of plexiform schwannoma may be challenging and require multiple surgeries. Spinal located tumor difficult to excised, due to extensive permeative pattern.
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- Yu D, Choi JH, Jeon I. Giant intradural plexiform schwannoma of the lumbosacral spine – a case report and literature review. BMC Musculoskelet Disord. 2020 Jul 11;21(1):454. doi: 10.1186/s12891-020-03492-y. PMID: 32652976; PMCID: PMC7354678.
- Ko JY, Kim JE, Kim YH, Ro YS. Cutaneous plexiform schwannomas in a patient with neurofibromatosis type 2. Ann Dermatol. 2009 Nov;21(4):402-5. doi: 10.5021/ad.2009.21.4.402. Epub 2009 Nov 30. PMID: 20523833; PMCID: PMC2861261.
- Berg JC, Scheithauer BW, Spinner RJ, Allen CM, Koutlas IG. Plexiform schwannoma: a clinicopathologic overview with emphasis on the head and neck region. Hum Pathol. 2008 May;39(5):633-40. doi: 10.1016/j.humpath.2007.10.029. PMID: 18439936.
- Amer SM, Ukudeyeva A, Pine HS, Campbell GA, Clement CG. Plexiform Schwannoma of the Tongue in a Pediatric Patient with Neurofibromatosis Type 2: A Case Report and Review of Literature. Case Rep Pathol. 2018 Oct 15;2018:9814591. doi: 10.1155/2018/9814591. PMID: 30410810; PMCID: PMC6205313