Diagnosis
Differential diagnoses
The differential diagnosis includes elastofibroma, fibrolipoma, desmoid-type fibromatoses, and nuchal fibrocartilaginous pseudotumor. Management
Simple excision is curative. However, in patients with Gardner syndrome, up to 45% will develop desmoid-type fibromatosis at other sites, and so this should be searched for and excluded. Patients can develop a recurrence, so follow-up is required. Epidemiology
This is a rare tumor, presenting over a wide age range, but usually in the 3rd to 5th decades of life. There is a slight male predilection, although this is not seen in syndrome associated patients. The most common site is the posterior neck, but may also be seen in other sites (extremities, lumbosacral area, buttocks, face). See also
Fibrous Lesions

References
Further reading
Lester D. R. Thompson; Bruce M. Wenig (2011). Diagnostic Pathology: Head and Neck: Published by Amirsys. Hagerstown, MD: Lippincott Williams & Wilkins. pp. 8:44–45. ISBN 978-1-931884-61-7.
However, serious forms can result in the following:
Stunted growth, deformity, and increased likelihood of fractures
Patients experience anemia, recurrent infections, and hepatosplenomegaly due to bone expansion leading to bone marrow narrowing and extramedullary hematopoiesis
It can also result in blindness, facial paralysis, and deafness, due to the increased pressure put on the nerves by the extra bone
Abnormal cortical bone morphology
Abnormal form of the vertebral bodies
Abnormality of temperature regulation
Abnormality of the ribs
Abnormality of vertebral epiphysis morphology
Bone pain
Cranial nerve paralysis
Craniosynostosis
Hearing impairment
Hypocalcemia

Malignant infantile osteopetrosis
Autosomal recessive osteopetrosis (ARO), also known as malignant infantile osteopetrosis or infantile malignant osteopetrosis (IMO), is a rare type of skeletal dysplasia characterized by a distinct radiographic pattern of overall increased density of the bones with fundamental involvement of the medullary portion. Infantile osteopetrosis typically manifests in infancy. Diagnosis is principally based on clinical and radiographic evaluation, confirmed by gene analysis where applicable. As a result of medullary canal obliteration and bony expansion, grave pancytopenia, cranial nerve compression, and pathologic fractures may ensue. The prognosis is poor if untreated. The classic radiographic features include endobone or "bone-within-bone" appearance in the spine, pelvis and proximal femora, upper limbs, and short tubular bones of the hand.