Multifocal Extra-Abdominal Desmoid Fibromatosis: A Rare Diagnosis

Abstract

A 36-year-old female patient seeks her primary care physician for a 2-year history of right back pain associated with diminished strength in her left arm. The patient is referred to our hospital following the findings of a computed tomography scan which shows a nodular, oval-shaped, soft tissue density mass located in the upper third of the right thoracic wall in intimate relation with the intercostal muscles. Above it, in close proximity with the right pulmonary apex and located in the thoracic inlet, there is another mass with the same tomographic characteristics. Surgical resection is conducted and final pathology results are consistent with multicentric, low grade fusocellular neoplasia. Later genetic testing by Sanger sequencing detects the mutation S45F in the CTNNB1 gene, confirming the diagnosis of multifocal extra-abdominal desmoid fibromatosis.