Large myofascial fibromatosis involving the shoulder girdle.AR Bhaskar, RS Dhir, M Desai, AA Mistry
Dept of Orthopaedics, KEM Hospital, Parel, Bombay, Maharashtra.
An 11 year old girl presented with gradually increasing swelling over left scapular region and limitation of movements. On examination, a mass with firm to hard consistency was found fixed to the scapula. Clinical diagnosis of fibromatosis was confirmed by needle biopsy. Radical excision of the tumor was carried out and the resultant large exposed area was covered by transpositional rotation of trapezius myocutaneous flap. Microscopic examination of excised tumor revealed spindle shaped elongated cells in the form of whorls and trabeculae. The post operative course of the patient was uneventful with no evidence of recurrence at the end of 22 months.
Keywords: Case Report, Child, Fascia, Female, Fibromatosis, Aggressive, surgery,Human, Muscle, Skeletal, Shoulder, Soft Tissue Neoplasms, surgery,
Fibromatosis - a term coined by Stout' constitutes a group of benign fibrous tumours characterized by slow growth, local invasiveness and a notorious tendency towards recurrence after surgery. These tumours proliferate locally and infiltrate the adjacent soft tissue even crossing the musculofascial plane, but they never metastasize hence the synonym non-metastasizing fibrosarcoma. Meuller in 1838 called these 'Desmoid tumour' referring to their tendon like consistency. Fibromatosis are broadly classified into two groups: Superficial (fascial) and deep (musculoaponeurotic) and involves all age groups but have predilection for young females.
An 11 years old female patient attended the hospital out patient department with complaints of gradually increasing swelling over left scapular region and limitation of movement of the left shoulder and elbow joints for 5 years. The swelling initially appeared over the left scapular region and over the years extended to the chest wall, into the axilia and the adjacent part of left arm restricting shoulder movement to a jog. The elbow was fixed in extension and attempted movements of these joints caused pain and was resented by the patient. About six months ago she had undergone a minor surgical procedure outside and was referred to this hospital. Patient's past history and family history were non-contributory [Figure - 1] and [Figure:2].
Physical examination revealed a large lobular mass 12 cm x 10 cm in size, firm-to-hard in consistency involving the infraspinous fossa of the scapula, the posterior axillary fold, and the chest wall. The swelling was fixed to the scapula but could be moved slightly over the rib cage. The overlying skin was shiny and firmly adherent to the swelling. The left shoulder was held in adduction and only 10 degrees of abduction and minimal rotation was possible. The swelling had extended to the arm posteriorly below the surgical neck of the humerus upto the spiral groove but was not fixed to the humerus. Attempted flexion of the elbow made the tense long head of triceps stand out like a cord. There was marked wasting of the muscles of the upper extremity (triceps, deltoid and biceps) but there was no neurovascular involvement.
With these findings a clinical diagnosis of fibromatosis involving the shoulder girdle was made. Needle biopsy done after admission concurred with the clinical diagnosis. Laboratory examination revealed no abnormality. A soft tissue shadow was discernible on plain X-ray of the shoulder region without any bony involvement. Plain X-ray of the chest and elbow showed no abnormality. Angiogram showed no tumour blush indicating a relatively avascular tumour mass.
Under general anaesthesia the tumour was excised with a margin of healthy tissue and the overlying adherent skin. The tumour involved long head of triceps from its origin at the infraglenoid tubercle to the spiral groove, the latissimus dorsi and teres major muscles from the inferior angle of the scapula to their insertion in the bicipital groove, posterior part of deltoid, teres minor and infraspinous muscles. The lateral border of the scapula was shaved off along with the tumour. The neurovascular structures (brachial vessels, radial, median, ulnar, and circumflex nerves) could be separated from the tumour easily and were retracted gently before excision of the tumour. The main difficulty was to get a wide margin through normal healthy tissue as the tumour is known to penetrate in fascial planes. The tumour bulk was removed en masse with piecemeal removal of parts which were adherent to the surrounding musculature. Care was taken to excise through normal uninvolved tissue.
This wide excision left an extensive raw area over the scapula, posterior part of upper third of the arm, axilla and the chest wail. The gleno-humeral joint was open and the neurovascular structures exposed [Figure:3].
A lower trapezius myocutaneous flap 20 cm x 8 cm based on descending branch of transverse cervical artery was transposed to cover the defect. The donor site was closed primarily by approximating the skin edges together. After surgery shoulder and elbow was stabilised over an aeroplane splint without any dressing to look for any colour changes in the flap. Post-operatively, there was no neurovascular complications and gradual mobilisation of shoulder and elbow was started after three weeks once the flap had settled [Figure:4]. The patient continued to follow up in our deposit. The range of movement at shoulder and elbow joints increased and there was no evidence of recurrence at the end of 22 months. (Whilst the natural history of desmoid tumour is unpredictable, most recurrences after wide excisions are seen within the first year. Absence of clinical recurrence at the end of 18-20 months is a favourable outcome.)
On gross examination, the tumour was firm to hard, cut with a gritty sensation and on cross section revealed a glistening white surface resembling scar tissue [Figure:5] and [Figure:6]. Microscopic examination revealed characteristic spindle shaped elongated cells arranged in interlacing bundles with a whorled and trabecular pattern. There was abundant collagen between the cells with cellular atypia and mitotic figures.
Desmoid tumours are extremely rare neoplasms and constitute less than 0.1% of all tumours. Although rarely seen in young children, their incidence increases at puberty and peak is seen between ages 25-35. There is a slight female preponderance in the earlier age groups (juvenile, fertile and menopausal categories), but in the senescent types, male to female ratio approaches 1:1. Familial incidence is rare though cases where several members of the same family are affected known.
The tumour has predilection for certain anatomical sites. In large series reviewed at the Armed Forces Institute of Pathology, out of 367 confirmed cases of fibromatosis the distribution of tumour was maximum in the musculature of the shoulder girdle (22.2%) followed by chest wall and back (17.2%), thigh (12.5%) and mesentery (10.5%). The tumour never metastasises but multi-centric origin and occurrence of multiple tumours in the same limb has been described.
Ultrastructural studies have revealed that the tumour arises from the myofibroblasts (fibroblasts with myofilaments) and these cells are also seen in granulation tissue of healing wounds. Though the aetiology of desmoid tumours remains speculative, there is increased frequency of desmoid formation secondary to trauma and surgical procedures, probably due to an inherited defect in connective tissue formation. A hormonal theory was suggested as early as in 1935. The role of estrogen in stimulating tumour growth has been documented and receptors for the hormone are found in the cytosol of the tumour cells. A familial type of desmoid tumour (Gardner's syndrome) occurring with intestinal polyposis has also been described possibly reflecting a common genetic basis.
The histological pattern does not reflect the growth potential of the tumour, hence recurrence cannot be predicted. Treatment is based on the extent and the anatomical relationship of the tumour. Radical excision of the tumour along with surrounding uninvolved structures is the treatment of choice and has been emphasised by Das Gupta and associates. Recurrent lesions can also be treated by local excision and adjuvant radiotherapy. Post-operative radiation is routinely recommended it the excision is close to, or, through the tumour. Radiotherapy controls local tumour growth and delays the onset of recurrence. Although its value has been disputed, recent reports have shown superior results with radiotherapy. The irradiation dose usually required is around 5000 to 6000 centigrays.
The role of anti-estrogens is unclear and treatment with progesterone, testosterone, and prednisolone have been disappointing. Recently, Tamoxifen, an anti-estrogenic drug, in high doses (2mg qds) has shown to cause regression of tumour size. However, further studies are required, in conjunction with estrogen receptors, to exploit its full therapeutic value . The role of chemotherapy is also controversial but reports suggest that chemotherapeutic agents may be useful in children where post-radiation cicatrization may cause deformities and premature growth arrest. Drugs given are vincristine, actinomycin and cyclophosphamide (VAC regime) for 6-12 weeks, if no response is seen adriamycin and dacarbazine are added. Therapy is discontinued at 16 weeks if no response is seen or earlier if the potential side effects outweigh the therapeutic efficacy.
Till understanding of the disease process further improves, and new insights are gained regarding the pathogenesis of desmoid tumour, its management will present a formidable challenge to the surgeon.
[Figure - 1]