SPR Unknown #84 -- FINAL
1 year old with left arm mass
Publication Date: 2004-08-17
1 year old with left arm mass. No history of trauma
MRI: (T1: figures 1-3), (T2: figures 4-6), (T2* GRE: figuers 7-10), (T1 post gadolinium: figure 11)
There is a large heterogeneous mass replacing the short head of the biceps brancii muscle. It extends from the most proximal portion of the biceps bracii tendon just anterior to the humeral head in the shoulder through the anterior upper arm to its distal insertion on the radial tuberosity.
Hemophilia is a descriptive term for several diseases characterized by bleeding resulting from defective clotting mechanisms. The disease is inherited in an X-linked pattern, so that females are the trait carriers and males present phenotypic evidence of the disease, but it can rarely be found in women. The clinically recognizable abnormalities in hemophilia result from abnormal bleeding and clotting. When hemarthrosis occurs, the direct effect of fresh blood and later hemosiderin deposit following blood absorption result in acute or chronic synovitis, subsynovial and capsular fibrosis, synovial hypertrophy, and vascular sclerosis. The ultimate result of chronic and repeated hemarthrosis is severe cartilage damage and articular fibrosis, often leading to ankylosis. In most patients with severe disease, bleeding episodes begin in early childhood. They often decrease in frequency as the child grows and may cease completely at puberty. Bleeding may occur into soft tissues (most commonly the calf, forearm flexor, and psoas muscle), with resultant hematomas under increased tension.
Bleeding into muscle or para-articular tissues is recognized as a mass desity with edema and distortion of the normal fat and fascial planes; heterotopic new bone formation (myositis ossificans) may follow. The knee, hip, and elbow are most commonly affected by joint hemorrhage. Joint hemorrhage can be distinguished from other types of effusion by MRI. Sonography is useful for hip effusions. With repeated or chronic hemarthrosis, synovial hypertrophy may follow, and MRI may be helpful in distinguishing chronic synovitis from new hemorrhage. After repeated bleeding cartilage begins to degenerate. This is first recognized as a loss of joint space. Once cartilage erosion is advanced, irregularity of the cortical outlines of the epiphysis and subchondral cystic lesions are seen.
The chronic heperemia induced by hemarthrosis may lead to advanced maturation and increased size of the affected epiphysis and adjacent structures. Stimulation of growth plate may result in extremity overgrowth, although premature growth plate fusion following hemorrhage into this segment may result in extremity shortening. The weakened areas of bone may fracture.
In this case, the lack of significant enhancement following gadolinium and the decreased signal on the gradient echo sequence (suggesting blood products) raise the question of a large hematoma. However, since some tumors may bleed, soft tissue sarcomas remain in the differential diagnosis.
- Ozonoff, M.B., PEDIATRIC ORTHOPEDIC RADIOLOGY, W.B. Saunders Company, 1992, 492-503.