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|LETTER TO EDITOR
|Year : 2015 | Volume
| Issue : 2 | Page : 268-270
Ulnar nerve tuberculoma masquerading as a neurofibroma
Debajyoti Chatterjee1, Khushboo Lath1, Ramesh Kumar Sharma2, Ashim Das1
1 Department of Histopathology, Post Graduate Institute of Medical Education and Research, Chandigarh, India
2 Department of Plastic Surgery, Post Graduate Institute of Medical Education and Research, Chandigarh, India
|Date of Web Publication||5-May-2015|
Department of Histopathology, Post Graduate Institute of Medical Education and Research, Chandigarh
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Chatterjee D, Lath K, Sharma RK, Das A. Ulnar nerve tuberculoma masquerading as a neurofibroma. Neurol India 2015;63:268-70
Tuberculous involvement of the peripheral nerve is extremely rare. A patient with an ulnar nerve tuberculoma was mistakenly diagnosed to be having a neurofibroma based on clinical examination and magnetic resonance imaging (MRI).
A 42-year-old patient presented with a 4-month history of a gradual onset weakness of the right hand and forearm. There was associated paresthesia and tingling sensation on the medial aspect of the hand. Gradually, the patient developed an ulnar claw hand. On neurological examination, there was loss of power on the medial aspect of hand and medial two fingers along with atrophy of the medial aspect of forearm and the hypothenar muscles. There was loss of pain, touch, temperature, and vibration sensation in the right forearm and hand along the ulnar nerve distribution.
On palpating the ulnar nerve, its focal thickening and swelling were noted on the posteromedial aspect of the arm just above the elbow. The swelling was fusiform in shape, well-defined, and measured 5 × 3 cm. The MRI showed a well-encapsulated, fusiform mass in relation to the ulnar nerve, that was hyperintense on T1WI and hypointense on T2WI signal [Figure 1]a and b. The clinical and radiological impression was that of a benign peripheral nerve sheath tumor, possibly a neurofibroma. The mass was excised under general anesthesia. An intracapsular excision of the mass was done with a few nerve fascicles (3 mm) proximal and distal to the lesion. On gross examination, the lesion was well-encapsulated and fusiform in shape. The cut surface was homogenous and showed a granular, caseous material in the center. The histopathological examination showed a well-encapsulated lesion with peripherally compressed nerve fibers. The lesion showed large areas of necrosis in the center surrounded by palisading histiocytes, occasional ill-formed epithelioid cell granulomas and a few Langhans giant cells [Figure 1]c and d. The Zeihl-Neelsen stain did not reveal any acid-fast bacilli.The lepra stain was negative. The overall morphology was consistent with a tuberculoma.
|Figure 1: (a) Axial T1WI MRI of the right lower arm showing a hyperintense lesion in relation to the ulnar nerve. (b) Coronal fat-suppressed T2WI of right elbow shows a hyperintense lesion on the ulnar aspect of the lower arm in relation to ulnar nerve. (c) Histopathological examination shows a well-encapsulated lesion with large areas of central necrosis (H and E, × 4). (d) Peripheral area shows ill-formed epithelioid cell granulomas admixed with lymphocytes (H and E, × 20). T1WI = T1-weighted imaging, T2WI = T2-weighted imaging, H and E = hematoxylin and eosin|
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On further evaluation, the patient denied any history of previous tuberculous infection or contact with patient suffering from tuberculosis. The Mantoux test was, however, positive. The patient was started on antituberculous therapy (ATT). At a 4-month follow up, the patient showed significant improvement in his sensory and motor functions. The residual deformity of the hand persisted.
Tuberculomas of the central nervous system (CNS) are more commonly seen in children and the preferred site is the cerebellum. Tuberculomas may also be seen within the spinal cord. Compared with its occurrence in the CNS, involvement of the peripheral nervous system is very uncommon. Secondary involvement of the nerve from an adjacent lymph node, bony, or soft tissue tuberculous abscess may be seen. However, a tuberculoma of a peripheral nerve is an extremely rare phenomenon. Only four cases of peripheral nerve tuberculomas have been reported in the English literature and all of them showed involvement of the ulnar nerve [Table 1]. ,,, Radiological imaging was available only in one case, that showed features similar to our patient.  Systemic tuberculous involvement was not present in 3 out of the 4 reported cases. 
The pathogenesis of a peripheral nerve tuberculoma is debatable. The epineurium is tough making it difficult for the tuberculous bacilli to penetrate it. It is believed that a tuberculoma involving a nerve is always secondary, possibly arising as a result of vascular dissemination from a primary focus (often residing in the lung). The primary focus is not detectable in a majority of the cases by imaging or other modalities as it may have either healed or may have been present as a very small, subclinical entity. The two cases reported in literature had a history of local trauma and contact with tuberculosis. , Local trauma may rarely be responsible for direct inoculation of the bacilli.
The preoperative diagnosis of a peripheral nerve tuberculoma may be difficult to establish because of rarity of this entity. The final diagnosis comes from the histopathological examination that reveals a central area of necrosis surrounded by epithelioid histiocytes, granulomas with or without giant cells. A complete intracapsular excision followed by antitubercular therapy can result in a good recovery of motor and sensory functions. The compilation of more cases with adequate radiological information would help to increase awareness of this entity and achieve an accurate preoperative diagnosis.
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Hasan SA, Prakash VE. Tuberculoma of the ulnar nerve. A new clinical entity. J Int Coll Surg 1964;42:30-4.
Sinha GP. Tuberculoma of the ulnar nerve. J Bone Joint Surg Am 1975;57:131.
Nucci F, Mastronardi L, Artico M, Ferrante L, Acqui M. Tuberculoma of the ulnar nerve: Case report. Neurosurgery 1988;22:906-7.
Ramesh Chandra VV, Prasad BC, Varaprasad G. Ulnar nerve tuberculoma. J Neurosurg Pediatr 2013;11:100-2.
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|[Pubmed] | [DOI]|