Elastofibroma dorsi (EFD) is a rare benign, non-encapsulated lesion characterized by the proliferation of elastic fibers in a collagenous stroma with adipose tissue (1). The lesion mostly occurs in the infrascapular region (2). As a result of the unspecific clinical presentation of the mass, it is difficult to make an accurate diagnosis based on clinical signs and symptoms alone (3). EFD is asymptomatic in the majority of cases and is mostly diagnosed incidentally on cross-sectional imaging studies of other indications (4). Pain appears to be the most frequent and main complaint in symptomatic cases, ranging from mild pain to severe disabling pain. The condition was initially described by Jarvi in 1961 as a rare lesion, and is currently classified as a benign fibroblastic/myofibroblastic tumor according to the 2020 World Health Organization (WHO) classification (5,6). The present study describes the case of a female patient with bilateral symptomatic EFD in the scapular region that affected her daily activity. In addition, a literature review of similar cases is presented. All the reviewed and cited studies have been confirmed to be credible (7).

The present study performed a mini-review of the literature in order to identify relevant studies on this type of tumor. The literature review involved a search on Google Scholar, employing key words, including ‘Elastofibroma dorsi’ and ‘bilateral elastofibroma dorsi’ to identify relevant studies. The literature review was also assessed based on the CASP checklist. A total of 15 studies on EFD were identified, including a total of 38 cases (Table I). The youngest case documented in the literature was that of a 39-year-old male who was 44 years younger than the oldest documented case, who was an 83-year-old female (4,8). As was expected, a predominance of the female sex was observed for the lesion, with a 2:1 female-to-male ratio. Although the majority of the identified studies stated that most of the cases were asymptomatic, only 4 cases out of the 38 (10.5%) cases exhibited no symptoms (2,9,10). Pain was the chief complaint in symptomatic individuals with other symptoms, such as discomfort and fatigue. Imaging analyses, such as ultrasound, CT scan and magnetic resonance imaging (MRI) were frequently used for diagnosis (11-17). Some studies utilized more than one imaging technique to further analyze the lesion and made a comparison between them (3,9-12,16). As regards the location of the lesion, infrascapular EFD was the most common in the identified literature, as also indicated by many other studies (7,11,12). Other sites included the suprascapular, subscapular and other regions of the back (Table I). As regards the laterality of the lesion, bilateral EFD was the most frequent. Surgery was the management of choice in the majority of the cases (89.5%).

EFD is a rare benign tumor of mesenchymal origin typically occurring in middle-aged women and elderly individuals (3). It is characterized by elastic fiber proliferation inside a stroma of collagenous adipose tissue (1). In a previous retrospective study on 4,435 chest CT scans, EFD was found incidentally in eight of them, indicating a prevalence of 0.8% (18). The lesion exhibited a predominance for the female sex, with a 2:1 female-to-male ratio (according to the authors' review) and a mean age of 76.6 years (18). The specific rationale behind the higher incidence of EFD in females remains unclear. However, Metin et al (19) observed that among the 72 females in their case series, the majority (66.6%) were housewives. This observation may indicate a potential association with the substantial time spent by housewives engaging in household activities that require the repetitive use of the upper extremities, such as cleaning and cooking (19). The same study revealed that the lesion was located on the right side in 49 of the total number of patients (n=84; 58.3%), on the left side in 16 (19%) of the patients, and was bilateral in the remaining 19 (22.6%). There appeared to be a statistically significant association between the dominant hand and the mass forming on the same side (19). A theory suggests that chronic and repetitive mechanical stress results in microtrauma, leading to the overproduction of elastic tissue from stimulated fibroblasts. This could explain the predilection for the dominant hand, given its more extensive use in daily activities (16). A previous study demonstrated there was no statistically significant association between either the sex or age of the patient and the size of the mass (18). The pathophysiology of the lesion remains unclear and is a matter of debate (3). In another study on 258 elderly individuals who had a chest CT scan, the prevalence of EFD was found to be 2% (20). On the other hand, another study reported the mass to be the most common, and it was found in 66% of the studied patients (5). As the lesion tends to be generally asymptomatic and has a slow grow rate, it may remain undiagnosed (2). However, the mass can still be identified in patients who experience symptoms, with pain being the most common complaint (3). In the case described herein, apart from pain, the mass also affected the daily activities of the patient, and she was not able to function normally. A number of risk factors have been shown to be associated with EFD; however, as aforementioned, the exact pathogenesis is not yet completely understood (2,3,16). The risk factors associated with the lesion can be both environmental and genetic (4). The friction of the lower scapula against the thoracic wall as a result of either manual labor or repetitive minor trauma is considered to promote the development of the lesion (3). This can be supported by the higher prevalence of the disease among manual workers and elderly patients (4).

Both clinical evaluation and imaging can aid in the diagnosis (2). Given that the majority of individuals do not exhibit symptoms, this lesion is typically discovered serendipitously during MRI and CT scans or incidentally during surgical procedures performed for other purposes (4). However, this may not involve bilateral EFD, as the authors' review of the literature revealed that most of the bilateral EFD cases had symptoms. An ultrasound is generally the first line of examination, as it poses no radiation damage to the patient, followed by CT and MRI scans. MRI, although not routinely required, can elevate diagnostic confidence as a result of its good soft tissue contrast (1,13). As per the standard diagnostic approach, an ultrasound was initially performed in the patient described in the present study, which revealed a solid mass with a size of 10x8x3 cm at the posterior-lateral aspect of the lower right chest wall. The mass was heterogeneously echogenic with no features suggesting any underlying rib destruction. The diagnosis was further aided by a CT scan, which revealed not one, but two bilateral suprascapular soft tissue masses that were both poorly defined and exhibited no infiltration of the adjacent structures nor any destruction of adjacent ribs. The definitive method for confirming the diagnosis is a histopathological examination. This examination typically reveals a mesenchymal tumor characterized by dense collagen bands interspersed with numerous irregularly arranged elastic fibers, separated by mature adipose islets (1). The results of the histopathological analysis of both masses in the patient described herein revealed proliferations composed of collagen fibers and large thick elastic fibers within a loose stroma infiltrating into the surrounding fibrofatty tissue. No cellular atypia or mitotic activities were found in the specimen.

As regards treatment options, these vary based on the presence or absence of symptoms, since simple observation is sufficient in asymptomatic cases (1). Surgical resection is reserved for cases where the tumor is sufficiently large in size and symptomatic (4). The case in the present study was managed surgically by removing the masses, as they affected the quality of life of the patient. The recurrence rate following surgical resection is between 0.06 and 4.5%, and hematoma and seroma formation are among the most common complications (19). While wide or radical excision is not deemed necessary, curative marginal resection is recommended, as incomplete excision has been reported to be associated with local tumor recurrence (1). Nevertheless, to the best of our knowledge, no instances of malignant transformation were identified in the existing literature (1,15). In the present study, the surgical outcome of the patient was good, with no recurrence and complications. The present study however, was limited by the absence of an MRI and immunohistochemical examinations, as well as the non-retrieval of CT scan images.

In conclusion, EFD is a rare benign tumor that can be symptomatic. Imaging is required for its diagnosis, and it typically forms within the upper back region. While the occurrence of this mass is infrequent, the prognosis is generally favorable. Post-operative recovery is typically uncomplicated, and the recurrence rates are low.