A 24-year-old presented with swelling in the wrist joint. Histopathological examination of the swelling revealed spindle cells with palisading of the nuclei and Verocay bodies. Which of the following is the most likely condition?

Explanation

## Correct Answer: B. Schwannoma The pathognomonic histological findings—**spindle cells with nuclear palisading and Verocay bodies**—are diagnostic of **Schwannoma** (also called neurilemoma). Verocay bodies are orderly arrangements of spindle cells with their nuclei aligned in parallel rows, separated by eosinophilic cytoplasm, creating a characteristic "fence-like" pattern. This is virtually pathognomonic for Schwannoma and distinguishes it from other neural tumours. Schwannomas are benign, encapsulated tumours arising from the Schwann cells of the nerve sheath. They present as solitary, slow-growing masses—in this case, a wrist swelling—and are typically painless unless they compress adjacent structures. The tumour is well-demarcated and can be surgically excised without damaging the parent nerve because the tumour grows eccentrically from the nerve. Histologically, Schwannomas show two patterns: **Antoni A** (cellular, with Verocay bodies) and **Antoni B** (loose, myxoid). The presence of Verocay bodies confirms Antoni A pattern, the hallmark of Schwannoma. This is a common NEET PG question testing recognition of this classic histological finding in a peripheral nerve tumour presentation. ## Why the other options are wrong **A. Neurofibroma** — Neurofibromas also contain spindle cells but **lack Verocay bodies**, which is the discriminating feature. Neurofibromas show disorderly arrangement of spindle cells without the organized nuclear palisading seen in Schwannoma. Additionally, neurofibromas are infiltrative (not encapsulated) and are associated with NF1 in multiple cases. The absence of Verocay bodies rules out Neurofibroma. **C. Glioma** — Gliomas are tumours of the central nervous system (brain/spinal cord), not peripheral nerves. They would not present as a wrist joint swelling. Histologically, gliomas show different cell types (astrocytes, oligodendrocytes) and lack the characteristic spindle cell morphology with Verocay bodies. The clinical presentation (peripheral wrist mass) and histology both exclude glioma. **D. Neurofibroma** — This is a duplicate of option A. Neurofibromas lack the organized Verocay bodies and nuclear palisading that define Schwannoma. The key discriminator is the **presence of Verocay bodies**, which is pathognomonic for Schwannoma and absent in Neurofibroma, making this option incorrect. ## High-Yield Facts - **Verocay bodies** (orderly nuclear palisading in parallel rows) are pathognomonic for Schwannoma and distinguish it from Neurofibroma. - **Schwannoma = Antoni A + Antoni B**: Antoni A is cellular with Verocay bodies; Antoni B is loose and myxoid; Verocay bodies = Antoni A. - **Schwannoma is encapsulated and eccentric** to the parent nerve, allowing complete excision without nerve damage; Neurofibroma is infiltrative. - **Schwannoma is solitary and sporadic**; Neurofibroma is associated with NF1 (multiple neurofibromas) and NF2 (bilateral acoustic neuromas). - **Schwannoma presents as a painless, slow-growing mass** in peripheral nerves (wrist, ankle, neck); malignant transformation is rare (<1%). ## Mnemonics **VEROCAY = Schwannoma** **V**ery **O**rderly **C**ells **A**rranged in **Y** pattern (parallel rows). Verocay bodies = pathognomonic for Schwannoma. Use this when you see 'palisading nuclei' in a peripheral nerve tumour. **SVAN: Schwannoma vs Neurofibroma** **S**chwannoma = **S**ingle, **V**erocay bodies, **A**ntoni A/B, **N**o NF1 association (sporadic). Neurofibroma = multiple, no Verocay, infiltrative, NF1-linked. ## NBE Trap NBE pairs "spindle cells" with both Schwannoma and Neurofibroma to test whether students know that **Verocay bodies are the discriminating feature**—many students confuse the two tumours because both contain spindle cells, but only Schwannoma has Verocay bodies. The duplicate option (D = A) is a distraction. ## Clinical Pearl In Indian clinical practice, Schwannomas of the wrist and hand are common benign tumours presenting as painless swellings; they are often discovered incidentally on imaging or during evaluation of a mass. Complete surgical excision is curative and safe because the tumour is encapsulated and does not infiltrate the nerve, unlike Neurofibroma. Histology with Verocay bodies confirms the diagnosis and guides management. _Reference: Robbins & Cotran Pathologic Basis of Disease, Ch. 28 (Peripheral Nervous System); Harrison's Principles of Internal Medicine, Ch. 379 (Tumours of the Nervous System)_