A case of invasive abdominal wall fibromatosis presenting as intra-abdominal mass

A 26-year-old lady presented with a palpable mass of one and half year’s duration, on the left side of her abdomen. It was painless but mild dragging sense was present. She had no history of fever, vomiting or any other complaint. She noticed the mass for the first time during her second trimester of third pregnancy. She had no history of previous surgery. Her bladder and bowel habits were normal. On general examination, patient was afebrile, vitals were stable. Mild pallor was present. Abdominal examination revealed a fairly globular non-tender mass measuring 20 cms across, occupying left flank and umbilicus. It was soft to firm in consistency and immobile. FNAC reported as benign spindle cell tumour. A contrast-enhanced computed tomography (CT) scan revealed a large heterogeneously enhancing well defined soft tissue intra-abdominal mass in left flank and left retroperitoneum with invasion of left flank muscles suggestive of benign soft tissue tumour with minimal ascites. At exploratory laparotomy, a mass of around 30 cm x 25 cm was present extending from anterolateral abdominal wall into the retroperitoneum with multiple feeding vessels present, without any solid organ adherence. The mass was excised completely. Gross examination of the cut section reveals firm whorled mass located within surrounded by skeletal muscle. Histopathological examination revealed an intrabdominal fibromatosis with densely collagenised stroma and dilated vessels with myxoid change. Microscopic picture of the tissue showed fish in a stream pattern and stellate cells. There were no intraoperative or postoperative complications. Patient was discharged on 8th postoperative day. Follow up till 2 years bears no evidence of recurrence.

Desmoid tumor represents an intermediate grade neoplasm with a striking predilection for locally invasive growth and recurrence following resection. More effective, well-tolerated non-surgical treatment options are needed. Current approaches: If feasible, watchful waiting is the preferred approach, 20-30% spontaneous regression. In situations where treatment is indicated, the following approaches are utilized:vSurgery is the primary approach if minimal morbidity is anticipated, Medical therapies, Cytotoxic drugs, Tyrosine kinase inhibitors, Hydroxyurea, Gamma secretase inhibitors. mTOR Inhibitor Rationale: Desmoid tumor is well-known to be associated with deregulation of the APC/beta-catenin pathway, Deregulation of the mTOR cell proliferation/survival pathway may play an important role in tumor biology when the APC/beta-catenin pathway is disrupted, The mTOR inhibitor sirolimus is attractive as a potential targeted therapy for desmoid tumor, Well-tolerated in children and young adults, Can be given orally in tablet or liquid formulation.

Recently, targeted therapies are being explored in desmoid-type fibromatosis (DTF). Unfortunately, effective treatment is still hampered by the limited knowledge of the molecular mechanisms that prompt DTF tumorigenesis. Many studies focus on Wnt/beta-catenin signaling, since the vast majority of DTF tumors harbor a mutation in the CTNNB1 gene or the APC gene. The established role of the Wnt/beta-catenin pathway in DTF forms an attractive therapeutic target, however, drugs targeting this pathway are still in an experimental stage and not yet available in the clinic. Only few studies address other signaling pathways which can drive uncontrolled growth in DTF such as: JAK/STAT, Notch, PI3 kinase/AKT, mTOR, Hedgehog, and the estrogen growth regulatory pathways. Evidence for involvement of these pathways in DTF tumorigenesis is limited and predominantly based on the expression levels of key pathway genes, or on observed clinical responses after targeted treatment. No clear driver role for these pathways in DTF has been identified, and a rationale for clinical studies is often lacking. In this review, we highlight common signaling pathways active in DTF and provide an up-to-date overview of their therapeutic potential.

Letter to the editor

The past year has led to significant changes in systemic therapies used to treat soft tissue sarcomas, mainly dominated by the removal of the recently approved drug olaratumab as part of combination therapy with doxorubicin from the NCCN Guidelines for Soft Tissue Sarcoma, according to Dr. Suzanne George. Several histology-specific drugs have entered the space, including pazopanib and pembrolizumab, the latter of which was approved as a category 2B recommendation for alveolar soft part sarcoma, highlighting the rather limited role of immunotherapy in sarcomas. Dr. George also discussed updated data for sorafenib in the treatment of desmoid tumors, as well as the importance of larotrectinib in TRK fusion-positive tumors.

We present a 13-year-old girl who had been operated for the intraspinal mass in upper thoracic spine and paraparesis with thoracic limited laminectomy and excision of the tumor mass elsewhere. The histopathological examination was reported to be aggressive fibromatosis. After 2 years, she presented again with 1-year duration of progressive deformity in the upper thoracic spine and weakness of both lower limbs. Focal kyphosis at T4-T5 was measuring 68°. Magnetic resonance imaging (MRI) showed recurrent tumor involvement of posterior elements of T2-T5 and paravertebral soft tissues with signal changes in the cord at T2-T5 vertebral levels with focal kyphosis and internal gibbus. She underwent posterior spinal revision decompression with internal gibbectomy and instrumented fusion. The histopathology showed features suggestive of aggressive fibromatosis. After wound healing at 2 weeks, she underwent 3-D conformal radiotherapy, based on the preoperative tumor extent on MRI (dose of 45 Gy in 25 fractions over 5 weeks). She had normal neurology at 2-year follow-up and was tumor free on MRI. Hence, aggressive fibromatosis can recur following successful surgical wide excision. Multilevel thoracic laminectomy in growing children can cause progressive spinal deformity and neurological deficits. Operative treatment of recurrent tumor involves en bloc excision with instrumented fusion followed by local radiotherapy. This is the first pediatric recurrent spinal fibromatosis reported with successful treatment as per author’s knowledge.