Since its first description by Järvi and Saxen in 1961 [
1], elastofibroma has been known as a rare benign tumor of unknown pathogenesis seen mostly in the elderly people. Although it is commonly found in the subscapular region beneath the rhomboid and latissimus dorsi muscle at the level of the sixth through eight ribs, uncommon locations have also been reported including, infraolecranon and subscapular region [
1,
4]. There are also a few reports of involvement at other sites including greater trochanter, deltoid region, ischial tuberosity and even tricuspid valve [
4]. Although bilateral involvement has been reported approximately 10% of patients, it is usually unilateral [
4,
5]. Our patient had bilateral mobile solid masses under the scapula and there was no tumor at any other sites of the body.
To understand ethiopathogenesis of elastofibroma dorsi, two main theories have been proposed, suggesting either true neoplasm or reactive tissue proliferation [2,4,6]. Because this tumor is often found in location exposed to mechanical stress, it may result from the friction of the scapula against the thorax and thus generating tumor growth, especially in lesion occurring bilaterally [5,8,9]. Several authors have emphasized the role of fibroblasts producing excessive amounts of elastic matrix as a result of constant trauma [1,2,5]. However, Marin et al [9], found no correlation between repetitive trauma and tumor formation. The patient discussed here, was a housewife and she has been not working so hard. Hence, we also thought that there is no correlation between tumor genesis and constant trauma as Marin et al [9] did.
In this disease, there was found to be an excessive amount of elastic material produced by fibroblasts as well as obstacles in the course of forming elastic fibers. Therefore, it was considered that this tendency was a sort of reactive hyperplasia taking place with a constitutional predisposition in the background. Histological findings consist of a mixture of intertwining swollen, eosinophilic collagen and elastic fibers, associated with occasional fibroblasts. They are embedded in a collagenous background that may show mucoid change and contains variously sized aggregates of mature fat cells [4,5]. Special elastic stains may be useful to contrast the elastic fibers from the collagenous ones [5]. Both of the tumors stained with Verhoeff’s elastic van Gieson exhibited similar histological findings as explained above. Swollen red collagen and black colored degenerated elastic fibers indicates microscopic diagnosis of the tumor apparently.
The imaging features of elastofibroma dorsi have been characterized in recent years [6,8]. Plain radiographs generally show no evidence of a soft tissue tumor. It usually of little value in diagnosing elastofibroma dorsi, occasionally it may show an elevation of the scapula and soft tissue density in the subscapular and periscapular area [8]. However, both CT and MRI have been used to reveal masses in patients with this tumor [6,8]. With either imaging technique, the tumor may have a characteristic appearance that includes streaky layers of soft tissue that are similar in signal intensity or attenuation to skeletal muscle and that are interspersed with areas of fat. CT scan of our patient revealed poor differentiation of tumor edges from surrounding muscles on the both sides. On MRI images, low signal intensities were found in both of the tumors in this case, which reflect the fibrous and collagenous nature of the masses and high signal intensities would reflect the presence of the fat tissue.
Although elastofibromas has been known a tumoral mass seen generally in the elderly people past the age of 55 years [2,5,6], it was rarely reported in the younger ones [3,8]. Majo et al [3] revealed two women having unilateral elastofibroma dorsi aged of 45 in their study. Our patient was 39-years-old and she was interesting being one of the few young patients having bilateral mass. We believe that a surgeon should always consider elastofibroma dorsi when palpate a mobile mass under scapula or see a heterogeneous mass between latissimus dorsi muscle and bony thorax on either CT or MRI even in younger patients. Complete resection is the best treatment when the lesion was symptomatic.
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