Elastofibroma dorsi: 8 case reports and a literature review

A series of 8 cases of elastofibroma is reported, and the clinical, pathological and imaging features and different therapeutic modalities are reviewed. On this basis, we suggest an algorithm for the diagnosis and treatment of elastofibroma. Briefly, marginal excision is the treatment of choice in symptomatic patients, while followup appears to be a good solution in asymptomatic ones.

ginal excision of the mass without performing a preliminary biopsy. Postoperatively, the operated shoulders were immobilized with a support for 3 weeks followed by rehabilitation and physical therapy. These patients were followed for a mean period of 27 months (range, 18-37 months). During this period, no recurrence of the elastofibroma was observed, and the patients were pain free with a completely normal shoulder range of motion.

Discussion
Elastofibroma is a rare lesion. In fact most publications [1][2][3][4][5][6][8][9][10] reported either a single case or a small series of 2-7 cases, except for Nagamine et al. [7] who reported a study of 170 cases. These lesions tend to be slowly growing and asymptomatic in more than 50% of the cases. When symptoms are present, they are typical, consisting of local scapular swelling and a clunking sensation during abduction and adduction of the shoulder, with pain of moderate or, rarely, severe entity [2,3,5].
The location of elastofibromas and its incidence among older individuals may be related to the natural existence of fibro-elastic tissue in this region and suggests a reactive process in response to friction of the scapula against the ribs [2,3,10]. Alternatively, the genesis of elastofibroma is thought to involve an overproduction of the collagenous connective tissue with a degeneration of the collagen fibres and an overproduction of immature elastic tissue, derived from fibroblasts, alternating with deposition of hyperplastic fat [2,8,10]. Genetic factors may also be involved [2,8,10].
Ultrasound examination shows an abnormal mass of tissue in the typical location of the elastofibroma with an alternating pattern of hyperechogenic and hypoechogenic lines that are roughly parallel to the chest wall ( Fig. 1). MRI is considered to be the investigation of choice because it shows the alternating pattern of fibrous and fatty tissues (Fig. 2). The lesions appear poorly circumscribed, heterogeneous with the margins that may be sharp and indistinct. On T1-weighted and T2-weighted sequences, fibrous tissue produces low-intensity signals identical to that produced by muscular tissue, while the fatty tissue is seen as a high-intensity signal on T1weighted sequences and as an intermediate signal on T2weighted sequences. Streaks of fatty tissue alternate with 34 J Orthopaed Traumatol (2008) 9:33-37 On STIR sequences, the mass is seen as a mosaic of low and high intensity areas. The elastofibroma appears as a large mass with ill-defined contours and marked gadolinium enhancement [6,[8][9][10]. CT is less sensitive than MRI in visualizing the fatty tissue, so that the elastofibroma may be seen as a homogeneous mass with a density inferior to that of muscles. Moreover, CT shows the absence of bone abnormalities.
Elastofibroma exhibits a characteristic structure where streaks of fatty tissue are alternated with strands of fibrous tissue. The hypertrophic fibrous tissue contains fibrillated material with identical staining affinities to that of necrotic fibrous tissue, muscle, and fat (Fig. 3).
Routine biopsy has been considered to rule out soft tissue sarcoma [4][5][6][7][8][9]. On the contrary, most of the recent publications indicate that biopsy is unnecessary when the MRI findings are sufficiently typical [1-3, 5, 6, 8]. In particular, 35 J Orthopaed Traumatol (2008) 9:33-37 Fig. 2a-d T1-weighted MR images. a Axial image shows a hypo-intense solid mass under the right scapula within the muscular tissue of the posterior thoracic wall. The diameter of this mass with a regular contour is 6.18 cm. b-d After the infusion of gadolinium with fat suppression technique, MRI shows a prevalent peripheral enhancement with a central hypo-intensity due to fat tissue. A ill defined mass appears without bone or surrounding soft tissue infiltration and is localized between the subscapularis muscle and the posterior thoracic wall  gested because it carries a low recurrence risk [1,5,[8][9][10], and no malignant transformation has been reported. Guha and Reja [1] mentioned the marginal surgical excision for these lesions and reported only one case of recurrence after the excision; another case was successfully treated with radiotherapy. Malghem et al. [6] adopted a wait and see approach in asymptomatic patients: since these patients did not develop symptoms, the authors concluded that elastofibroma is an ungrowing lesion after the diagnosis.
Considering these reports, we suggest a diagnostic and therapeutic algorithm for elastofibroma (Fig. 4). In case of a scapular region mass in an elderly woman, radiography, ultrasound and MRI with gadolinium enhancement are required. If the patient is asymptomatic and there is no enhancement on MRI, clinical follow-up is sufficient. On the other hand, in symptomatic patients with no enhancement, marginal excision of the mass is necessary. Marginal excision is also indicated in the absence of symptoms in the presence of enhancement on MRI. We recommend biopsy to rule out sarcoma when both symptoms and MRI enhancement are present.