Is Shoulder Impingement One of the Reasons for Elastofibroma Dorsi ? Radiological and Clinical Analysis of 13 Patients

Abstract

Background

Elastofibroma dorsi (ED) is a rare benign soft tissue tumour that usually occurs in the subscapular region of the back. Clinical presentation often includes the presence of a painless, slowly growing mass in the infrascapular region, which may be accompanied by shoulder discomfort or restricted movement.

Objective

This study aimed to contribute to the existing literature on the long-term outcomes of Elastofibroma dorsi by examining a series of 13 patients’ clinical features, imaging data, demographical data, and pre- and post-operative functional scores and also to investigate the relation between Elastofibroma dorsi and shoulder impingement.

Method

We have retrospectively analysed the radiological, clinical, demographical, and functional data of 13 patients from a single centre. Ipsilateral shoulder X-rays are examined for shoulder impingement using radiological parameters such as acromiohumeral distance, lateral acromial angle, and acromial index. The functional scores, including Constant Score, Q-Dash, and VAS were evaluated.

Results

There were 13 patients (9 females and 4 males) with a mean age of 59.9 years (range 53–68 years). The mean follow-up was 65.6 months (range 11–131 months). The tumour side was right in 6 (46%) patients and left in 5 (38%) patients, and the tumour was diagnosed bilaterally in 2 patients (15%). The pre-operatively mean Constant Score was 67.3 and improved to 85 post-operatively (p < 0.001). Pre-operatively, the mean quick-DASH score was 35.3 and improved to 15, 5 post-operatively (p < 0.001). Pre-operatively, the mean VAS score was 5.4 (range 0–10) and improved to 1.69 (range 0–5) post-operatively (p < 0.001). Pre-operatively, the mean flexion value was 137.7° and improved to 161.2°.

Conclusion

Our results show that shoulder impingement due to acromion abnormality could be relevant to scapulothoracic dyskinesia and ED. Further studies are needed to reveal the exact etiopathogenesis of ED

Introduction

Elastofibroma dorsi (ED) is a rare benign soft tissue tumour that usually occurs in the subscapular region of the back [1]. It represents 1–2% of all primary tumours of the chest wall [2]. ED primarily affects elderly individuals, with a higher prevalence in women. Although its exact aetiology remains unclear, chronic mechanical stress, vascular and genetic factors have been implicated in its development [3]. Histopathologically, ED is characterised by abundant elastic fibres and fibrous tissue [4]. Clinical presentation often includes the presence of a painless, slowly growing mass in the infrascapular region, which may be accompanied by shoulder discomfort or restricted movement [5]. Although it can be bilateral, it is predominantly unilateral [6]. Management strategies for ED are contingent upon the presence of symptoms and the impact on the patient’s quality of life. Asymptomatic cases may warrant conservative monitoring, whilst surgical excision becomes a consideration when symptoms are present and adversely affecting the individual’s well-being. Surgical excision is the primary treatment modality, especially in cases where the tumour causes functional impairment or aesthetic concerns. Long-term prognosis is generally favourable, with a low recurrence rate [1]. ED is a distinctive soft tissue tumour requiring careful clinical evaluation and appropriate diagnostic imaging to ensure accurate diagnosis and timely intervention for optimal patient outcomes. Computed tomography (CT) scans and magnetic resonance imaging (MRI) can confirm diagnoses and an important role in understanding the complexities of ED.

Scapulothoracic dyskinesia is an abnormal motion of the scapula on the thoracal cage and it can be caused by a wide range of factors, including muscular imbalance, injury at the shoulder girdle, overuse, etc. The abnormal movement of the scapula can cause a limitation in shoulder function, including reduced ROM, muscle weakness, pain, and discomfort with motion. It is shown that the main cause of these changes at the shoulder and surrounding structures is shoulder impingement, which is most likely relevant to scapulothoracic dyskinesia. Although the relationship between scapulothoracic dyskinesia and shoulder impingement was controversial, recent studies have proved that scapular motion affects not only shoulder ROM but also the subacromial space [7]. Its treatment is usually treating the underlying conditions. Physiotherapy is essential for cases that are developed because of musculoskeletal conditions. There are also other theories about the aetiology of the ED, including vascular and genetic theories. Some authors think vascular theory is the real mechanism behind the development of ED. Their chief argument is that ED primarily affects elderly women, which shows vascular insufficiency in this group causes reactive fibromatosis and secondary degeneration of elastic fibres. Also, genetic theory advocates that these patients have a familial enzymatic disorder that makes these patients predisposed to the development of ED.

We aimed to contribute to the literature about long-term outcomes of ED by examining clinical features, imaging data, demographical data, and preop/postop functional scores of our series of 13 patients. We especially focussed on the ipsilateral shoulder’s x-ray to find a correlation between ED existence and radiographic changes in the shoulder, if any. We thought ED can be caused by scapulothoracic dyskinesia, which can also cause shoulder impingement, and therefore it should change radiological parameters about shoulder impingement. Patients who are operated on with the diagnosis of ED are evaluated retrospectively to reveal any relationship between this diagnosis and shoulder impingement.

Patients and Methods

We evaluated 17 patients retrospectively that are operated in our clinic, Istanbul University, Istanbul Medicine Faculty, Orthopaedics and Traumatology Department between 2010 and 2023. Meticulous surgery is essential for the excisional surgery of the ED. The most common complication of this surgery is seroma formation. Good haemostasis and proper placement of the drainage tube are important components of this surgery. Four patients were excluded because of a lack of follow-up data (3) and shoulder operation (1). Their imaging data were collected from Extreme PACS (Ankara, Turkey). Ipsilateral shoulder X-rays are examined for shoulder impingement using radiological parameters such as acromiohumeral distance, lateral acromial angle, and acromial index (AI) [8]. These parameters are usually used to evaluate subacromial impingement and rotator cuff tear. Acromiohumeral distance is the length of the vertical line drawn from the bottom of the acromion to the top of the humeral head [9] (Fig. 1). The measurement is typically obtained from an AP (anteroposterior) shoulder radiograph. It is a valuable radiographic parameter for assessing rotator cuff tears and subacromial impingement. A decrease in acromiohumeral distance is indicative of rotator cuff tear and may also be suggestive of rotator cuff arthropathy as well as subacromial impingement.

Fig. 1.

Acromiohumeral distance (the length of the vertical line that is drawn from the bottom of the acromion to the top of the humeral head) and lateral acromial angle (the angle between a perpendicular line lateral to the glenoid and a horizontal line parallel to the acromion undersurface)

Second, a lateral acromial angle is the angle between a perpendicular line lateral to the glenoid and a horizontal line parallel to the acromion undersurface [10] (Fig. 1). The lateral acromial angle is an angular measurement that is utilised for the assessment of the slope of the acromion in relation to the glenoid. A lower angle has been shown to narrow the subacromial space, thereby increasing the risk of impingement.

Third, the AI was defined as the ratio between the distance from the plane of the glenoid cavity to the lateral edge of the acromion and the distance from the plane of the glenoid cavity to the lateral edge of the humeral head [11] (Fig. 2). It basically quantifies the lateral extension of the acromion over the humeral head. The measurement is obtained from a true AP shoulder radiograph. A higher AI may be indicative of rotator cuff tears and subacromial impingement. A senior orthopaedic surgeon made all these measurements, and unfortunately, blinding could not be applied because of the study design. We obtained an average value of these values from the literature and compared our series.

Fig. 2.

Acromial index [distance from the glenoid plane to the acromial lateral border(A) and is divided by the distance from the glenoid plane to the lateral aspect of the humeral head(B)]

Even though it differs from view to view, its mean value is nearly 8.5 mm (range 7–12 mm) [9]. When it comes to the lateral acromial angle, it is measured between the articular surface of the glenoid and the inferior surface of the acromion. It is shown that the average value of the lateral acromial angle is 78° [10]. Lastly, the AI is the distance from the glenoid plane to the acromial lateral border divided by the distance from the glenoid plane to the lateral aspect of the humeral head [11]. It is shown that the average value of normal AI is between 0.63 and 0.67. These values are often considered in the clinical status of shoulder impingement. However, we thoughtED could be caused by scapulothoracic dyskinesia, which can also cause shoulder impingement. So, these values can also indicate the diagnosis of ED. Although there are some clinical tests, like Neer and Hawkins-Kennedy to evaluate shoulder impingement clinically; we can’t include those tests since our study is retrospective. Their demographical data (including gender, age, age on surgery, occupation) clinical features (including dominant side, lesion side, symptom status, family history, region of the tumour, ROM of the shoulder joint, old functional scores) X-rays that belong to operation time and preop functional scores are collected from our archive. Each radiological parameters are measured on their old X-rays. Lastly, they are invited to an appointment for actual functional scores, including Constant Score, Q-Dash, and VAS. Constant Score was first described by Constant et al., and it was specifically designed to assess the shoulder joint’s functional status. It evaluates pain, the activity of daily living, range of motion, and strength [12]. Q-Dash score (an abbreviation for The Quick Disabilities of the Arm, Shoulder, and Hand Score) is a self-administered test to evaluate disabilities in these joints. The test was first described by Beaton et al., and it is a shorter version of the DASH score [13]. The current ROM of the shoulder and functional scores are noted as well.

Statistical Analyses

All statistical analyses were performed utilising the Statistical Package for Social Sciences (SPSS^®) version 29.0 software. The Kolmogorov–Smirnov and Shapiro–Wilk tests were used to check all measurements for normality. A paired-t test was conducted to make meaningful comparative analyses of the constant, quick-DASH, VAS scores, and range of motion degrees during the pre-operative and final visits.

A two-sided p value is used to compare functional scores and range of motion in IBM SPSS Software. (Tables 1, 2) Also, their mean values of radiological parameters about shoulder impingement were compared to mean values in a healthy population. (Table 3) Their new shoulder X-rays were taken to check for any signs of shoulder pathology, if any.

Table 1.

Comparison of functional scores pre-operatively / post-operatively

	Preoperative	Last control	p value
Constant Score	68.1(range 57–85)	85.3 (range 69–95)	0.001
Q-Dash	32.7 (range 13–54.5)	15.6 (range 4–31.8)	0.001
VAS	5.1(range 0–10)	1.7(range 0–5)	0.001

Table 2.

Comparison of ipsilateral shoulder ROM pre-operatively / last control

ROM	Preoperative	Last control	p value
Flexion	140° (range 90–175)	160° (range 130–175)	0.019
Abduction	130° (range 85–165)	155° (range 125–170)	0.011
Internal rotation	40° (range 20–65)	60° (range 50–65)	0.002
External rotation	60° (range 40–85)	80° (range 65–90)	0.001

Table 3.

Comparison of ipsilateral shoulder’s radiological parameters in this cohort / healthy population

Measurements on X-ray	Our series	Healthy population
Acromiohumeral distance (mean)	6.4 mm (range 5.3–12 mm)	7–12 mm
Lateral acromial angle (mean)	71° (range 61–85)	77°
Acromial index (mean)	0.74	0.63–0.67
Presence of shoulder arthrosis	None

Results

There were 13 patients (9 females and 4 males) with a mean age of 59.9 years (range 53–68 years). The mean follow-up was 65.6 months (range 11–131 months). The tumour side was right in 6 (46%) patients and left in 5 (38%) patients, and the tumour was diagnosed bilaterally in 2 patient (15%). Five of them were employed in physical labour works, five in office work, and three of them were unemployed and none of them had a family history. Eight patients had a painful mass that caused restriction of ROM of the shoulder, whereas three reported only a painful scapular mass without any limitation. Two patients were asymptomatic except for a painless mass. All 13 patients underwent complete resections. Preoperative shoulder X-rays showed no significant omarthrosis sign in any patient. The seroma formed in 4 patients (31%) post-operatively. During follow-up, there was a newly diagnosed ED in 2 patients (15%) on the contralateral side.

The pre-operatively mean Constant score was 67.3 (range 57–85) and improved to 85 (range 69–95) post-operatively (p < 0.001). Pre-operatively, the mean quick-DASH score was 35.3 (range 13–54.5) and improved to 15.5 (range 4–31.8) post-operatively (p < 0.001). Pre-operatively, the mean VAS score was 5.4 (range 0–10) and improved to 1.69 (range 0–5) post-operatively (p < 0.001) (Table 1). Pre-operatively, the mean flexion value was 137.7° (range 90–175) and improved to 161.2° (range 130–175) (p = 0.016). Pre-operatively, the mean abduction value was 130° (range 85–165) and improved to 156.1° (range 125–170) (p = 0.01). Pre-operatively, the mean internal rotation value was 37.7° (range 20–65) and improved to 60° (range 50—65) (p = 0.001). Pre-operatively, the mean external rotation value was 57.7° (range 40–85) and improved to 83.1° (range 65–90) (p < 0.001) (Table 2). In our cohort, the mean acromiohumeral distance was 6.29 mm, which is between 7 and 12 mm in a healthy population. The mean lateral acromial angle was 70.77°, which is nearly 77° in a healthy population. The mean AI was 0.75 mm, which is between 0.63 and 0.67 mm in a healthy population (Table 3).

Discussion

ED was first described by Jarvi et al. [14]. Historically, there have been notable changes and developments in understanding ED. But there is still debate and controversy on its pathological aspects [15], the selection criteria for surgery [16], the type of surgical procedure [17–19], and the pathogenesis of the lesion [3, 20, 21]. Table 4 shows the demographical data of studies from the literature.

Table 4.

Shows the study demographics data

Study	Year	Country	Study design	Sample size	Mean age, years	Male:female	Mean Follow-up, months
Lococo et al. [24]	2013	Italy	Retrospective cohort	71	60.2	23:48	59.32
Abat et al. [26]	2012	Spain	Retrospective cohort	37	57	22:15	84
Hammoumi et al. [25]	2014	Morocco	Retrospective cohort	76	49	22:54	-
Deveci et al. [27]	2017	Turkey	Retrospective cohort	51	55.3	6:45	26.9
Bartocci et al. [1]	2017	Italy	Retrospective cohort	82	60	27:55	64.7

Pathogenesis

Although genetic, vascular, and mechanical factors are blamed for the aetiology of ED in the literature, mechanical conditions, especially scapulothoracic dyskinesia, are prominent [3]. Metin et al. found that ED was more common on the dominant side in their study [22]. This increases the suspicion that the aetiology is mechanical. On the dominant side, abnormal friction due to scapulothoracic dyskinesia probably causes chronic and repetitive stress, which leads to pathophysiological changes for the development of Elastofibroma Dorsi. Although the number of physical labour workers and office workers was the same in our study, the literature showed that it is more common in physical labour workers [23]. Second, some authors think vascular theory is the real mechanism behind the development of ED. Their chief argument is that ED primarily affects elderly women, which shows that vascular insufficiency in these groups causes reactive fibromatosis and secondary degeneration of elastic fibres. Fukuda et al. discovered an abnormal elastogenesis in elastofibromas, which is caused by an abnormal arrangement of microfibrils. The data obtained in their study suggest that unique elastinophilic fibres of the elastofibroma are not simply a degenerative condition but are formed by an abnormal process of elastogenesis [20]. Nevertheless, that being more common in elderly women not only supports the vascular theory but also the genetic theory. Genetic theory advocates that these patients have a familial enzymatic disorder that predisposes them to the development of ED [21]. Since it is more common in women, researchers emphasised that there might some genes that are responsible for the development of ED and also X-linked inherited. We do not have enough data to evaluate our series for both vascular and genetic theories either.

Pathological Characteristics.

Although the diagnosis of all of our cases are pathologically confirmed, since this study does not involve collaboration with the pathology department, no data regarding pathological aspects could be obtained.

Selection Criteria for Surgery.

In comparing our study with the existing literature on surgical selection criteria, we didn’t have any certain criteria except symptoms, including pain and aesthetic concerns.

Surgical Techniques.

There are different types of surgical techniques described in the literature, including the latissimus dorsi muscle flap [18] or resection with scapulothoracic arthroscopy [19]. Still, we prefer marginal excision of the tumour with open surgery as defined before, which is mostly similar to the literature.

The objective of our study is primarily to investigate the potential correlation between ED and shoulder impingement. Even though there are several studies in the literature with larger patient series on ED, most of them have focussed primarily on clinical presentation, surgical outcomes or incidental findings. The distinguishing feature of our study is that it is the first to evaluate not only the functional status of the ipsilateral shoulder but also its radiographic characteristics, with a specific focus on subacromial impingement. In our study, we measured the radiological parameters related to shoulder impingement to explore the possibility that shoulder impingement may cause ED due to abnormal friction and scapulothoracic sliding. We also assessed patients’ functional status by evaluating ROM and functional scores. F. Lococo et al. observed that bilateral disease is not uncommon, with a prevalence of 17%, similar to our study’s findings (15%) [24]. These data indicate that vascular and genetic theories are involved in the development of ED and may explain why we do not see shoulder impingement in all patients diagnosed with ED. In their study, Hammoumi et al. examined X-rays of the patients, but their analysis was focussed on the tumour region rather than the ipsilateral shoulder. As anticipated, the radiographs were typically found to be normal. [25] Despite other studies in the literature that primarily focus on clinical presentation and surgical outcomes, our study is the first to investigate and prove the existence of subacromial impingement in patients diagnosed with ED.

The limitations of our study are that it was retrospective, pre-operative shoulder impingement tests could not be examined, it was single-centred, a lack of implementation of blinding at measurement of parameters with a small sample size. It is vital to recognise that the relatively small number of patients represents a key limitation in this field of research. Another limitation of the study was the lack of radiological measurements performed by an independent radiologist and the absence of interobserver evaluation. Further studies will help us to improve our understanding of the development of ED.

Conclusions

In this retrospective cohort, the ROM of the shoulder joint significantly improved as a result of excisional surgery. Functional scores of patients significantly improved as well. Although scapulothoracic dyskinesia is considered the main aetiological factor of ED; omarthrosis, one of the results of the scapulothoracic dyskinesia, is not found in this cohort. However, radiological parameters such as acromiohumeral distance, lateral acromial angle, and AI differed from mean values in a healthy population [8].

Due to its painful characteristic, surgical excision is required in symptomatic patients. In the post-operative period, seroma formation is one of the common problems. To prevent seroma formation, meticulous surgery and good haemostasis are essential. In the follow-up, the surgeon should be careful about new occurrences of ED on the contralateral side in the late postop period.

Our results show that shoulder impingement due to acromion abnormality should be a reason for scapulothoracic dyskinesia and ED. Although the number of physical labour workers and office workers are same in our study, since radiological parameters differ from the healthy population, we think the mechanical theory is prominent in the development of ED. Clinicians can gain awareness about the development of ED in patients, especially those with subacromial impingement as indicated by X-ray imaging. In addition, the findings of this study suggest that subacromial impingement can be considered a contributing factor to the development of ED. In cases where patients have not experienced adequate pain relief following their ED surgery, subacromial impingement treatments may be considered as a therapeutic option. Further studies are needed to reveal the exact etiopathogenesis and improve our understanding of Elastofibroma Dorsi.

Funding

There is no funding source.

Declarations

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical Approval

This study was approved by the institutional review boards of our university medical faculty hospital.

Informed Consent

Informed consent was obtained from all individual participants included in the study. This study was performed in Istanbul University Faculty of Medicine.