A previously healthy woman in her fifties contacted her general practitioner due to a troublesome lump on her hand that had progressed over the course of a year. The final diagnosis surprised those involved and serves as a reminder to both general practitioners and specialists.
The patient showed her general practitioner a lump that developed spontaneously, approximately 5 × 5 mm in size, in the middle of the palm of her left hand. The lump had grown slowly and was tender to touch. When she knocked it, she felt shooting pains towards her thumb. Her general practitioner performed an ultrasound examination and concluded that the tumour was consistent with a ganglion.
Lumps on the hands are common issues in general practice. The vast majority of lumps in the hand and wrist are benign and give no cause for concern (1, 2). Ganglions are the most common. They arise from a joint capsule or tendon sheath (tendon sheath ganglion) and are usually located on the back of the wrist. Primary treatment should not be surgical because the lumps often resolve spontaneously, and recurrence following surgery is common. Aspiration, surgical removal or endoscopic removal is appropriate if symptoms are long-lasting and substantial.
The second most common soft tissue tumours of the hand after ganglions are tenosynovial giant cell tumours. Apart from ganglions and giant cell tumours, which together make up the majority of soft tissue tumours of the hand, lipomas, granulomas and fibromas are common benign solid soft tissue tumours (2).
Small, superficial and asymptomatic lumps on the hands can be managed with observation and without any intervention. Patients with typical symptomatic ganglions, as described above, or small superficial lumps not involving deeper structures, can be referred to a local hospital or hand surgeon for removal without further diagnostic investigation. If the diagnosis is uncertain, further investigation should be considered. Lumps that grow rapidly, cause unusual symptoms or are more deeply sited must be investigated. The same applies if the tumour is suspected to be located close to major nerves or vessels. In these cases, an MRI scan is recommended. Ultrasound can identify fluid content and is predominantly of use in differentiating between superficial ganglions and solid tumours. X-rays should be taken if skeletal involvement is suspected. The National Competence Centre for Sarcomas at Oslo University Hospital has drawn up a flowchart to show which patients with soft tissue tumours should undergo investigation with MRI scanning and which should be referred to a sarcoma team (3) (Figure 1).
The general practitioner referred the patient to the orthopaedic department at the local hospital. The orthopaedic specialist found exploration and removal of the lump under local anaesthesia to be indicated with a working diagnosis of ganglion. When the surgeon touched the tumour peroperatively, the patient felt intense radiation to the thumb and up the arm. The tumour seemed to consist of nerve tissue and somewhat resembled a schwannoma. Since the patient did not have a ganglion after all, the procedure was discontinued without the tumour being removed.
An uncomfortable, but almost unavoidable situation in surgery is expecting to find one thing but finding something else entirely. In this case, it was surprising not to find a ganglion, but rather a tumour situated in or on a large nerve. The combination of inadequate anaesthesia and a more complicated tumour than anticipated meant that the surgery could not continue. In these cases, it is correct to discontinue dissection, take a tissue sample for histological analysis if possible, and refer the patient to a sarcoma centre.
The patient was then referred for an MRI scan at a private clinic and subsequently to the orthopaedic department at the regional hospital. Following the MRI scan, the radiologist reported a contrast-enhancing, well-defined soft tissue tumour adjacent to or on the median nerve at the outlet of the carpal tunnel. It was concluded that the tumour was consistent with a schwannoma, but that another type of tumour could not be ruled out (Figures 2 and 3).
Along with neurofibromas, schwannomas are the most common benign peripheral nerve sheath tumours. Schwannomas arise from Schwann cells in the nerve sheath, generally grow eccentrically and are well-defined. While neurofibromas also arise from the nerve sheath, there are differences to schwannomas, including concentric growth and less well-defined borders. In neurofibromas, it is not uncommon for the nerve fibres to run through the tumour, which can make dissection challenging. Benign nerve sheath tumours are often painful and sometimes cause neurological deficit (4). Symptomatic peripheral nerve sheath tumours in the hand should generally be surgically removed.
The lump was troubling the patient, and so she was offered surgery under general anaesthesia. The images from the MRI scan were provided to the radiologists at the regional hospital. The working diagnosis was a schwannoma involving the median nerve. After division of the carpal ligament, we reached the tumour, which was located on the median nerve where it branches into the hand. The tumour was approximately 10 × 10 mm and well-defined, and could be dissected from the nerve, apart from the thenar motor branch, which went through the tumour and had to be resected. The nerve branch could be sutured without requiring a nerve graft. On macroscopic examination, the tumour most resembled a schwannoma, but due to invasion of the nerve neurofibroma was a close differential diagnosis. A tissue specimen was sent for histological analysis.
A few days later, the provisional results from pathology reported that morphology was consistent with a malignant tumour, with both synovial sarcoma and malignant peripheral nerve sheath tumour being possible differential diagnoses. There was tumour tissue at the resection margin in one small area. Immunophenotyping confirmed that the patient had a synovial sarcoma, French malignancy grade 3 (Figures 4 and 5).
The term given to describe the unplanned marginal excision of a tumour that turns out to be a sarcoma is a whoops procedure, due to the surprise experienced. The concern is that it may spread tumour cells and complicate subsequent, more radical excision. The phenomenon was first discussed in 1985 and is quite common, particularly with smaller tumours with no typical malignant characteristics (5, 6).
The patient was immediately informed about the biopsy result and referred to a sarcoma centre. The preoperative images from the MRI scan were re-assessed by radiation oncologists. They concluded that there was a solid vascularised tumour along the median nerve with no typical 'target sign' or 'fascicular sign' as often seen in benign nerve sheath tumours. It was not possible to make a more precise diagnosis on the basis of the preoperative MRI images. Chest CT, abdominal CT and ultrasound of axillary nodes revealed no signs of metastases. A repeat MRI scan of the hand showed no residual tumour. Due to the tumour's location adjacent to a major nerve and tendons, an expanded resection was not advised. The patient received postoperative radiotherapy, 2 Gy × 30, to reduce the risk of local recurrence. At the next follow-up, the wounds had healed following the radiotherapy. The patient had no nerve pain or neurological deficit.
The patient has given consent for the article to be published.
The article has been peer-reviewed.