Rheumatology International (2019) 39:2129–2136 Rheumatology https://doi.org/10.1007/s00296-019-04381-x INTERNATIONAL IMAGING Intermetatarsal bursitis as frst disease manifestation in diferent rheumatological disorders and related MR‑imaging fndings Omar M. Albtoush1,2 · Theodoros Xenitidis3 · Marius Horger1 Received: 18 June 2019 / Accepted: 10 July 2019 / Published online: 18 July 2019 © Springer-Verlag GmbH Germany, part of Springer Nature 2019 Abstract Metatarsalgia defned as pain at the plantar aspect of the forefoot. Intermetatarsal bursitis is considered one potential soft- tissue cause of metatarsalgia that is presumably under-estimated, under-investigated, and, consequently, often misdiagnosed. To assess the role of MRI in the elucidation of the cause of metatarsalgia in patients with diferent autoimmune disorders presenting primarily with this symptom and to present the accompanying clinical and radiological fndings of intermetatarsal bursitis. Retrospective evaluation of the medical records of patients with diferent rheumatological conditions claiming pri- marily of pedal pains suggests metatarsalgia and who underwent, therefore, all magnetic resonance imaging between March 2010 and April 2018. Of them, six patients fulflled these criteria and were diagnosed subsequently with intermetatarsal bursitis. Several underlying autoimmune conditions were diagnosed. All patients were clinically assessed by the squeeze test and radiologically investigated with MRI; three patients underwent additional sonography. All patients presented intermeta- tarsal bursitis as frst disease manifestation. The number of involved bursae ranged from one to three on one side. The main MR fndings were distension of the intermetatarsal bursa with increased signal intensity on T2-weighted and post-contrast fat saturation T1-weighted images. Most frequent locations were the second and third intermetatarsal spaces. The size of the intermetatarsal bursitis and its plantar extension were correlated in all patients. Intermetatarsal bursitis can potentially be the frst manifestation of diferent rheumatological diseases. Awareness of this potential association as well as cognizance of its imaging fndings can help for making a more accurate and prompt earlier diagnosis of the underlying disease changing also the therapeutic approach. Keywords Intermetatarsal · Bursitis · Metatarsalgia · Squeeze test · Foot MRI Introduction Metatarsalgia is a common symptom in patients with rheu- matological disorders, though it can occur also from many causes [1]. In the setting of, e.g., rheumatoid arthritis (RA), * Omar M. Albtoush metatarsalgia generally is related to tendinitis of the fexor [email protected] digitorum tendons or to arthritis of the metatarsophalangeal Theodoros Xenitidis (MTP) joints, and can manifest symmetrically or asymmetri- [email protected] cally [2]. However, other diferential diagnoses exist and Marius Horger should be considered in this setting. The intermetatarsal [email protected] bursitis (IMTP) is one of them, and notably, its incidence 1 Department of Radiology, Eberhard Karls University in RA patients seems to be high (up to 90%) according to Tuebingen, Hoppe-Seyler-Str. 3, 72076 Tuebingen, Germany prospective ultrasound studies [3, 4]. Thereby, only few 2 Department of Diagnostic and Interventional Radiology, patients are symptomatic and its occurrence is expected University of Jordan, Queen Rania Str, 11942 Amman, later in the course of the disease [4]. The MTP joints and Jordan the foot tendons can be involved also in other autoimmune 3 Department of Internal Medicine II, Eberhard Karls disorders including systemic lupus erythematosus (SLE), University Tuebingen, Otfried-Mueller-Str. 10, systemic sclerosis (SSc), mixed collagenous diseases, 72076 Tuebingen, Germany Vol.:(0123456789)1 3 2130 Rheumatology International (2019) 39:2129–2136 psoriasis arthritis (PsA), etc. [5, 6]. However, in a frst report the next step, a search for metatarsalgia as the frst occurred on the prevalence of bursal infammation in SLE-patients, symptom was done in all these patients. At our outpatient Mukherjee found 100% involvement of intermetatarsal and clinic, about 4600 patients with rheumatological/autoim- submetatarsal bursae, however, without specifying if symp- mune diseases are taking care of yearly. About 10% of them tomatic or not [6]. Moreover, these authors did not difer- are new cases. entiate between intermetatarsal and submetatarsal bursae The retrospective data analysis/institutional review board which seem to be of diferent causes as the latter have no was approved by the ethic committee at our university and all synovial lining [4]. In all other autoimmune disorders, the patients gave their written consents. Six consecutive patients incidence of IMTP seems, however, to be rare as the spe- (all female; mean age 35.8 years; range 20–59 years,) with cialty literature on this topic is scarce, whereas, in RA, MTP RA/SLE overlap syndrome (n = 1), RA/Sjögren syndrome involvement is more common and frequently symmetrical; overlap syndrome (n = 1), RA (n = 1), psoriasis arthritis in the other mentioned diseases, it can occur isolated or be (n = 2), and RA/spondyloarthritis were retrospectively ana- asymmetrical which makes diferentiation from mimics like lyzed for correlation of imaging and clinical fndings. Morton’s neuroma or intermetatarsal bursitis (IMTB) more challenging [7–10]. IMTB, on contrary, is more often iso- MRI protocol and imaging analysis lated with only few cases experiencing multiple synchro- nous manifestations. As the clinical examination alone is Conventional MR imaging was performed on three 1.5 T not enough for making an accurate diagnosis, foot imaging, MR units (Siemens Espree, Siemens Magnetom Avanto, in particular MRI, is gaining an essential role in patients Siemens Magnetom Aera, and one 3 T Siemens Magnetom experiencing metatarsalgia. Hence, recognition of IMTB as Skyra, all Siemens Healthcare, Erlangen, Germany) with an independent cause of metatarsalgia implies knowledge a protocol that included a minimum of axial non-contrast of its imaging features as well as awareness of the potential spin echo T1-weighted, coronal fat saturation time spin echo clinical setting for its occurrence. Moreover, MRI and ultra- T2 (STIR)-weighted, as well as post-contrast fat saturation sound are the best imaging techniques, capable to detect and axial + coronal T1-weighted images. The T1-weighted spin characterize IMTB and in particular to diferentiate it from echo sequences were performed using a TR = 555–731 ms its mimics. Knowledge of local anatomy helps for correct and a TE = 11–14 ms. The STIR sequences were acquired diagnosis and exclusion of potential diferentials. Aware- using a TR = 4000–5560 ms, TE = 54–108 ms, and ness of the potential of developing IBMT as a frst disease TI = 150 ms (1.5 T) and 200 ms (3 T). The post-gadolinium manifestation in autoimmune disorders other than RA is a T1-weighted sequence was performed with parameters that prerequisite for an early diagnosis and its clinical relevance were identical to non-enhanced T1-weighted sequences with derives from the potential for primary targeted therapy (e.g., fat saturation. Slice thickness varied among the sequences steroid infltration) [11]. being 2–3 mm with 10% gap. Matrix size varied between The purpose of this retrospective image analysis was two- 256 × 143 and 320 × 150. The feld of view was adapted to fold: to assess the role of MRI in the elucidation of the cause the patient size (250–350 mm). Standard-dose contrast mate- of metatarsalgia in patients with diferent autoimmune dis- rial was administered in all patients. orders presenting primarily with this symptom, and to dem- Two radiologists with 25 and 10 years’ experience in onstrate the imaging features of IMTB as documented by MSK diagnosis retrospectively analyzed all MR images of MRI and ultrasound and to address diferences to its mimics. the forefeet. MR signal characteristics were analyzed on both T1-weighted and T2-weighted images as well as on fat-saturated post-contrast T1w images. We registered the Materials and methods signal intensity and contrast enhancement in MTP joints as well as the number of IMTB. The signal intensity was clas- Patient series sifed normal vs. hypointense vs. hyperintense. Bone marrow edema was registered as well as teno-synovial abnormali- This was a retrospective evaluation based on a patient data ties. We measured the size of IMTB in the coronal plane search for IMTB between March 2010 and April 2018. (mm) and the number and localization of involved IMTB. While reviewing the institute database, we searched for all The distance of plantar extension of the IMTB below a plane patients presenting directly or being referred to our in-house joining the interior cortex of the nearby metatarsal bones ambulatory for suspicion of rheumatological or autoimmune has been correlated as an objective mean to investigate the disorder, thus identifying all new patients confrmed later plantar extension of the IMTB toward the corresponding with time as having sufering of one of these diseases. In neurovascular bundle (Fig. 1). 1 3 Rheumatology International (2019) 39:2129–2136 2131 with 13 years’ experience in ultrasound diagnostic of the joints carried out the ultrasound examination. Results Patients Retrospective evaluation of the medical records between March 2010 and April 2018 identifed six patients with diferent rheumatological