Proliferative myositis
Proliferative myositis (PM) is a rare benign inflammatory myositis. It is sometimes classified as a subtype of a pseudosarcomatous proliferative soft-tissue lesion.
Epidemiology
Thought to commonly occur in middle-aged adults (around 50 years), but has also been described in children.
Clinical presentation
Patients may present with a rapidly enlarging solitary, firm and painful soft-tissue mass.
Pathology
It is characterized by infiltration of basophilic giant cells and proliferative fibroblasts within the affected region. Its exact etiology is not well known although an antecedent recent local trauma has been documented in some cases.
Location
There may a predilection for the head and neck region or upper extremities .
Radiographic features
Ultrasound
Described features include patchy areas of hyperechogenicity, containing hypoechoic lines preservation of continuous muscle bundles.
MRI
- T2: may show an ill-defined, hyperintense, intramuscular lesion, containing isointense lines
- T1 C+ (Gd): there may be subtotal enhancement with non-enhancing geometrical web and fascial enhancement sometimes been described
Treatment and prognosis
Its clinical course is benign and local recurrence following simple excision is considered uncommon.
History and etymology
It was first described by H E Kern in 1960 .
See also
