Schwannoma, also called neurilemoma or neurinoma, is the most common benign tumor of peripheral nerves that occurs in the upper extremity. The tumor has its origin in the Schwann cells, it can be solitary or multiple and it can have a slow growth over time. The tumor is spherical in shape, it has shiny, white surface and elastic consistency, being easily mobilized only on a transverse range of motion, not longitudinally.^1-4

Neurilemomas often appear on the flexor surface of the forearm and hand, they can be painless and the mean age of appearance is between 30-60 years old. It has no predilection whatsoever linked with sex or racial aspects.^1,5,6

Patients affected by schwannomas complain about paresthesia during or after work, sometimes motor inability or radiating pain in the range of distribution of the affected nerve. Painless schwannomas have also been reported: in these cases, the patient notices the mass only if it is large enough to be felt during palpation.^1,4 The diagnosis is based on clinical presentation, clinical exam and other paraclinical investigations such as magnetic resonance imaging (MRI), computed tomography (CT), electromyogram or nerve conduction study.⁵ It is necessary that the whole excised tissue, or at least a sample of the tumor is sent for a complete histopathological analysis, so that the origin of the tumor is confirmed. After surgical removal, recurrence rates are low, and the benign character of the tumor, makes surgery the only effective treatment.^2,4

Case report

A female patient was admitted in our hospital from 20.11.2017 to 21.11.2017 to undergo surgery for removal of a left ulnar nerve tumor that had been previously found by MRI and electromyogram (EMG) studies. The patient, who is right-handed, was 54 years old at that time and resided in the country side.

The history of the tumoral onset, as stated by the patient, showed that the abnormal growth developed approximately 1 year before the admission, having a relatively fast evolution rate. The patient also remembered that she had suffered before this a few episodes of trauma at the level where the tumor appeared.

From the personal pathological history of the patient we have to point out that she suffered from chronic gastritis, stage III hypertension treated with medication and diet, and mild mitral valve insufficiency. The patient also had a total hysterectomy in 2012. At admission we found that the medication she took daily consisted of bisoprolol (beta-blocker) 5 mg once daily in the morning, and pramiracetam (memory booster) 1 pill/day. She wasn’t a smoker, and didn’t drink alcohol.

Prior to admission in our unit, she had 3 examinations that confirmed the diagnosis of a nerve tumor. The first one, a rheumatology consult, concluded: "on the trajectory of the ulnar nerve a tumoral mass can be visualized” and the recommendation was plastic surgery follow-up and treatment. The second examination, an electroneuromyography revealed a difference in the intensity of signal between the stimulation of the left and right ulnar nerves, thus the conclusion of the neurological consult was that she had a left ulnar neuropathy. The third exam was an MRI, performed only 4 days prior to admission for surgery in our unit, which revealed: "a circumscribed well-defined area, with the diameter of 20 millimeters, located in the superior third of the posterior forearm, between the flexor carpi ulnaris muscle and the flexor digitorum profundus muscle, with T2 (weighted image) and PD (proton density) hypersignal, intermediate T1 (weighted image) signal, relatively homogenous and with intense contrast enhancement, without infiltration of the surrounding structures”.

Clinical exam showed no abnormalities of the respiratory, renal, skeletal, nerve and digestive systems. Blood tests revealed no significant abnormalities. The patient had normal blood pressure during admission, and took her daily pills as usual. The local exam confirmed the diagnosis: in the superior third of the left forearm, on the posterolateral ulnar border we could feel a round-like, deeply located, elastic mass, with the diameter of approximately two cm, which could be easily mobilized on the underlying structures. The patient accused pain when palpation was performed. Sometimes while resting she felt paresthesia in the fourth and fifth fingers of the left hand.

After having gathered all of the complex aspects that built-up our diagnosis of left ulnar nerve tumor, we decided that surgical removal was the correct and only option for our patient.

The patient underwent general anesthesia and was given a prophylactic dose of antibiotic while surgery was performed (amoxicillin + clavulanic acid). We opted for a short longitudinal incision (two-three cm) at the site of the tumoral mass – proximal third of the forearm, on the ulnar border. We dissected through the anatomical structures at this level: fat, fascia and through the flexor carpi ulnaris to identify the ulnar nerve and the tumoral mass at this level. We observed a round-shaped mass, well delimited by the surrounding structures, of approximately two cm in diameter, having the same color and consistency of the ulnar nerve (Figure 1). Very carefully we dissected the tumor circumferentially from the surrounding nerve branches under optical magnification with loupes, while reducing the damage of the nerve structure to a minimum. After removing the mass, we sutured the nerve to itself, thus removing any free space inside its structure. The flexor carpi ulnaris was also repaired. Thorough hemostasis was performed using electrocoagulation, simple sutures were made to close the skin and afterwards a dressing and cast were applied. The excised mass was sent for histopathological examination, so that the origin of the tumor could be identified.

Figure 1. Surgical view of the ulnar schwannoma

The histopathological result showed a well-delimited nodular tumoral mass, with limited areas of dense cells (Antoni A corpuscles), with tumoral cell nuclei disposed "in palisades”, surrounding fibrillar, dense, eosinophilic structures (Verocay corpuscles) and lax, edematous areas (Antoni B areas). The tumoral cells were fusiform, had medium height and abundance, with pale, eosinophilic cytoplasm, tachychromatic nuclei and minimum cyto-nuclear pleomorphism. The conclusion stated that the histopathological aspect was compatible with the diagnosis of schwannoma.

The patient left the hospital the next day after surgery, after changing the dressing. The swelling and inflammation were minimal, the dressing was clean, with minimum bleeding. The outcome of the procedure was good, with no complications. We advised the patient to come twice a week for check-ups, until removal of the sutures at two weeks post-operatively. At the first post-operative visit, 3 days after discharge, the patient showed no bleeding from the surgical site, minimal inflammation, no pain and a significant improvement in sensitivity in the fourth and fifth fingers. The cast was removed at the same time with the sutures, after 2 weeks, which was the total follow-up time. At this last check-up, the patient had no complaint whatsoever concerning pain, numbness or functional problems after surgery and was very satisfied by the result. Inflammation was absent, she felt no paresthesia and the scarring process was evolving favorably. We advised the patient not to lift heavy weights and to refrain from intense physical activity until 3 months after surgery. Also, we advised the patient to come back for further evaluation one month after surgery and then at three, six and twelve months.

Tumoral masses of the upper limbs can have significant functional and psychological impact. Some of these masses can be malignant and thus life-threatening. Although schwannomas are the most common tumors of the upper extremity,¹we cannot be sure of a growth’s origin without consulting a pathologist. A differential diagnosis of the schwannoma must be made with neurofibromas, which are pretty common as well, but more difficult to excise,^1,4 and with other conditions such as lipomas, fibromas or ganglia.⁴ Schwannomas have very rare reports of malignant transformation. Recurrence rates are also very low.^1,2 That is why it is very important that the procedure is performed correctly, removing the entire tumoral mass, so that the patient can resume one’s normal life. Sometimes the patients may need physical therapy, but this wasn’t necessary in the case we have reported.

Before admission, it is very important that a complete imaging study is performed, in order to locate with precision and quickly the site of the tumoral mass during surgery. MRI and ultrasound can be very helpful. It is also important to establish a well-documented family history to rule out neurofibromatosis.⁷

Intra-capsular enucleation is the best method to apply while surgically removing the tumors, because it reduces to a minimum both the damage to the nerve structure, and the post-operative recovery time.^4,8 The incidence of post-surgical deficiency is between 5% and 15%.¹ It is crucial that surgery is performed at the early onset of the symptoms, so that the tumoral mass doesn’t evolve in size, thus making the excision much more complicated. Our main surgical goal was to dissect as carefully as possible the tumor from the surrounding nerve, without further damaging it. From our experience with this case, and many others, we advise surgeons to use loupes for magnification, so that no extra damage is made while enucleating the schwannoma. The next step was to ensure that the mass had a benign character, thus a histopathological review was of great relevance. After the microscopic examination set the diagnosis, no further action was necessary, having excised the whole tumor. To aid the recovery, a cast should be set at the site of the excision so that the healing process of the nerve is not influenced by muscle movements. Further investigations are not necessary if the tumor is totally removed and if it has a single location site, because of its benign character. The patient can resume normal activity after removal of the cast and sutures, but we advise any patient to withdraw from intense sports that involve the operated hand for at least three months after surgery. We also recommend clinical check-ups at one month, three months, six months and 12 months after surgery, to identify any onset of possible post-operative neuropathies and to manage any scarring issues. Sometimes a silicone-based gel for aiding the scarring should be advised, especially in younger patients, who have a predisposition for hypertrophic scars.

We presented a case of a 54 years old female patient, with a schwannoma in the left ulnar nerve. Although this kind of tumors are the most common in nerve pathology and have a benign character, their symptoms can have a huge impact on the patient. Paresthesia in the fourth and fifth fingers of the left hand and pain when palpating the area were the main complaints of our patient.

Surgical approach is mostly important, because it is the only way to treat this kind of tumoral mass. A thorough imaging investigation will help assess the location and number of masses. In our case, three previous exams were performed before the admission of the patient. MRI, EMG and rheumatology consults revealed the character and the description of the tumoral mass. The follow-up in the first two weeks post-surgery allowed us to observe that the nerve wasn’t injured, the motor and sensory functions being preserved. Although the immediate post-operative assessment was good, we advised the patient to come back for further evaluation after one, three, six and 12 months. After the 1 month check-up, the patient was feeling very good, she had returned to work and she reported no pain in the ulnar nerve territory and no sensory loss.

Even though schwannomas can be a common finding in nerves, there is no "gold standard” of treatment. Surely, every experienced surgeon should approach the tumor with an incision above the mass site, and enucleate it by dissection from the surrounding nerve, but there is no guarantee that the patient will recover 100% post-operatively. That is why, in our case we try to present all the aspects from before surgery, during it or after, that can aid plastic surgeons to fully treat a complex case such as the present one. A complete medical team made of a plastic surgeon, radiologist, neurologist, rheumatologist, pathologist, physical recovery therapist and even a psychologist should work together to solve this complex problem that is represented by schwannoma.

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5. Mayo Clinic Staff. Peripheral nerve tumors. Accessed on: 01.01.2018. Available at: https://www.mayoclinic.org/diseases-conditions/schwannoma/cdc-20352974

6. Dickey ID. Neurilemmoma. Accessed on: 01.01.2018. Available at: https://emedicine.medscape.com/article/1256405-overview

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