myositis ossificans ( mo ) is a rare condition characterized by non - neoplastic heterotopic bone formation in soft tissue and skeletal muscle .
, it occurs mainly due to contact injuries which cause contusions , bruises and strains , or overuse due to intensive training . in this article
, we describe a 32-year - old swimmer , who developed mo due to overuse during an intensive swimming program .
a 32-year - old woman was referred by a general practitioner to our center , with progressive onset of pain in the left upper arm over the past 2 weeks .
he suspected a muscle rupture ; however , no specific onset of pain could be remembered .
she trained approximately 6 days per week for more than 10 hours during the last 3 months .
she experienced some fatigue ; however , she never experienced any sprain injury or trauma to the upper extremities .
clinical examination at the time of presentation showed a well - defined small nodule on the posteromedial part of the triceps .
however , deep flexion in the elbow and forced anteflexion of the shoulder were painful .
standard anteroposterior and lateral radiographs [ figure 1 ] showed sharply demarcated lesion , with partially mineralized zones in the periphery , located in the posteromedial soft tissues of the upper arm 
 ultrasound [ figure 2 ] confirmed the peripheral calcified lesion in the medial head 
 of the triceps .
all these aspects were compatible with an active phase of myositis ossificans circumscripta ( moc ) .
a computed tomography scan [ figure 3 ] confirmed the tentative diagnosis of moc because of the presence of peripheral mineralization and perilesional edema .
anteroposterior and lateral x - ray at first presentation showing that the lesion is located posteromedially of the midshaft of the upper arm .
the lesion is characterized by a sharply demarcated and partially mineralized periphery initial ultrasound confirmed the peripheral calcification of the lesion in the medial caput of the triceps .
the diameter of the lesion was 1.7 cm computed tomography of the lesion showed the characteristic peripheral calcification of the lesion .
there are no cortical or bone marrow abnormalities the patient was treated conservatively with rest and anti - inflammatory drugs .
control radiographs [ figure 4 ] and ultrasound [ figure 5 ] demonstrated a more sclerotic lesion after 2 months , which gradually disappeared after 6 months .
x - ray of the lesion 1 year after diagnosis and conservative treatment , showing complete resolution ultrasound of the lesion 1 year after diagnosis and conservative treatment , showing complete resolution one year later , recovery was complete with resolution of the lesion and a normal pain - free mobility of the shoulder and elbow .
control radiographs [ figure 4 ] and ultrasound [ figure 5 ] demonstrated a more sclerotic lesion after 2 months , which gradually disappeared after 6 months .
x - ray of the lesion 1 year after diagnosis and conservative treatment , showing complete resolution ultrasound of the lesion 1 year after diagnosis and conservative treatment , showing complete resolution one year later , recovery was complete with resolution of the lesion and a normal pain - free mobility of the shoulder and elbow .
mo can be classified into three types using the classification of noble : 1 ) myositis ossificans progressiva or fibrodysplasia progressiva ( fop ) is a severe , hereditary metabolic disorder .
it appears in children and is characterized by a diffuse and generalized metamorphosis of muscle into bone , but with a fatal outcome .
2 ) traumatic myositis ossificans circumscripta ( traumatic moc ) follows a local acute or chronic trauma , a repetitive trauma or chronic overuse in sports .
3 ) myositis ossificans circumscripta without history of trauma ( non - traumatic moc ) usually occurs in patients with hemophilia , paraplegia or poliomyelitis , chronic infections , burns or severe head injuries .
the lesions can occur at any age , but the highest incidence is reported in the second or third decade of life .
any muscle can be affected , but the most frequent locations are the anterolateral aspect of the thigh and upper arm .
non - traumatic moc is less frequent and seems to have no preference for gender .
again , adolescents and young adults under the age of 30 years are most often affected .
since non - traumatic moc is less frequent , no preferential anatomical site can be described .
mo in athletes has been well described.[515 ] this population predominantly suffers from myositis ossificans traumatica , most likely because of contusion or sprain injuries.[57915 ] however , very few reports mention overuse as an etiologic factor .
it is known that a muscle contusion produced by an external force is sufficient to damage the muscle and cause hemorrhage and muscle necrosis .
the blood vessels are torn , and thus the blood - borne inflammatory cells gain direct access to the injury site .
the magnitude of the inflammatory response depends on two main factors , namely , the severity of injury and the degree of vascularization of the tissue at the time of injury .
this inflammatory response stimulates fibroblasts and undifferentiated stromal cells to migrate to the connective tissue .
the release of multiple enzymes at the place of injury can stimulate the differentiation of fibroblasts into osteoblasts and calcification formation .
new bone formation is the result of increased vascularity , metabolism and excess calcium due to hyperemia of the injury .
the frequency of occurrence of mo is higher with moderate to more severe types of injuries ; however , this does not correlate with the duration of disability .
overuse , on the other hand , has an unknown pathophysiology in the development of mo .
it is believed that overuse causes accumulation of anaerobic metabolic waste products and lactic acid , leading to muscle vulnerability .
its repetitive character , especially in endurance sports , results in diminished perfusion and further muscle damage , thereby initiating an inflammatory reaction .
this seems to be enough to encourage the differentiation of the fibroblasts into osteoblasts with the development of mo . on a review of literature ,
we could only find two articles in which the development of mo is caused by overuse .
the first report was published in 1987 by gast et al . , who described the development of mo in a 16-year - old girl involved in intensive competitive sports , mainly during the 800-m running racethe second report was published in 2007 by webner et al . who described myositis ossificans traumatica in a 42-year - old recreational runner .
he experienced progressive pain during the course of a marathon competition , without notice of a specific event of onset or blunt trauma .
moc can easily be mistaken for osteomyelitis or a malignant tumor , specifically osteosarcoma or soft - tissue sarcoma . as a rule
, there is a rapid onset of pain and palpable swelling which can occur spontaneously or as a result of trauma .
further evolution and progression evolves in two stages.[24 ] first there is the active phase with pain progression for the first 2 - 3 weeks , after which maturation of the lesion occurs and pain diminishes slowly .
sometimes a flexion contracture and restricted movement can be observed because of the muscular invasion .
occasionally , there is an elevation of c - reactive protein , white blood cell count and alkaline phosphatase due to muscle inflammation and necrosis resulting from the lesion .
sometimes patients present with minor fever ; however , a good general condition is mostly preserved .
unfortunately , up to 40% of tumor lesions are heralded by a traumatic episode , and therefore history alone is not able to exclude these lesions .
standard radiographs should be performed at first presentation and are useful for follow - up .
further investigations in the early stage , before maturity of the lesion , include ultrasound and computed tomograms .
ultrasonography can detect these lesions at a very early stage before there are radiological signs .
the earliest radiological findings appear only within 1 - 3 weeks after the onset of pain .
the lesions present as an inhomogeneous soft - tissue mass , with maximum opacity at the periphery and a central radiolucent zone .
there is no cortical disturbance , and occasionally , there can be some periosteal reaction .
computed tomography is the gold standard for diagnosis in the early stages of the lesion .
99mtc - diphosphonate bone scintigraphy shows increased uptake of tracer in injured muscles , even before radiographic appearance . magnetic resonance imaging ( mri )
the mri findings are almost always non - specific , but can be present before the appearance of calcifications .
moc appears as a well - defined , inhomogeneous soft - tissue mass . in the early stages , an isointense nodule on t1-weighted images
. a central irregular hypointense zone and diffuse enhancement of the surrounding muscle or soft tissue is seen . in most cases ,
spontaneous resorption is the rule , and therefore surgical excision of the lesion is not necessary .
it is suggested that smaller lesions and those of the upper extremity are more likely to resorb completely , while large lesions and those occurring near insertion or origin of the muscle are more likely to persist .
treatment should consist of symptomatic support with anti - inflammatory drugs and relative rest , especially at the early stage of the disease .
there is no evidence for the use of indomethacin despite its widespread use in preventing heterotopic ossification after surgery . during the recovery phase ,
the patient should concentrate on progressive rehabilitation within the limits of pain , prevention of re - injury and regaining full range of motion if limitation occurred .
. surgical excision should only be considered in cases of persistent painful masses , repeating inflammation , debilitating function and/or doubtful diagnostics with need for histological investigation.[1421 ] in non - traumatic moc , surgery can be performed at any time , while the post - traumatic lesions can only be removed safely and completely after maturity to prevent recurrence .
cases in which , despite conservative treatment , a painful mass persists , surgical excision can be considered .
 myositis ossificans is a rare condition characterized by non - neoplastic heterotopic bone formation in soft tissue and skeletal muscle . 
 it is a benign and often self - limiting disease with no need for surgery . here , we describe a young female swimmer with myositis ossificans circumscripta of the triceps due to overuse . 
 because of the benign character of the lesion , conservative treatment was initiated with rest and anti - inflammatory drugs . 
 she obtained complete resolution after 6 months and was able to return to normal sporting activities . 
 myositis ossificans circumscripta is a rare benign lesion with an excellent prognosis . 
 most lesions in athletes occur due to contusions or strains ; however , overuse is now described as well . 
 spontaneous resolution is seen in almost all cases . 
 cases in which , despite conservative treatment , a painful mass persists , surgical excision can be considered . 
INTRODUCTION
CASE REPORT
Outcome
DISCUSSION
CONCLUSION