Asian Journal of Orthopaedic Research

Spindle cells named on the basis of their appearance under microscopy are found in both healthy tissues and tumors. Spindle cells look long and slender shaped cells on microscopy. Extra abdominal Fibromatosis is common in patients between puberty and 40 years of age group with female predominance.  A 15 years old male admitted with complain of pain and swelling in his right arm for 1.5 years without any history of antecedent trauma. Swelling was insidious in onset and gradually progressed to become the size of about 8 *6 cm.

MRI of right arm showed lobulated altered signal intensity lesion of size 63*41*84mm (AP*TR*CC) in lateral aspect of mid arm involving deltoid and triceps muscle with few enlarged lymph nodes. PET CT was suggestive of FDG avid soft tissue density in the lateral aspect of right mid arm involving mid arm muscles sparing the underlying bone and overlying skin with ipsilateral axillary lymph nodes involvement.

Using posterior lateral approach to arm wide excision of the tumor done protecting the radial nerve. Postoperative follow-ups showed no neurological deficit in upper limb.