Longus colli tendinitis mimicking a retropharyngeal abscess in a 12 year old girl. CA Hilditch1, S Biswas2, S Mathur1 1. Departments of Neuroradiology Lancashire Teaching Hospitals NHS Foundation Trust Preston, UK 2. The Walton Centre, NHS Foundation Trust Liverpool, UK

Purpose To demonstrate the diagnostic dilemma caused by a rare case of longus colli tendinitis presenting as a retropharyngeal abscess with unique imaging features

Case report: Clinical A 12 year old girl with no significant past medical history presented to the emergency department complaining of severe neck pain On examination: Marked restriction of neck movements with severe pain Pyrexia Redness and swelling of the left side of the neck Mild trismus and swallowing difficulty due to pain Blood biochemistry showed raised inflammatory markers and a neck ultrasound demonstrated reactive lymphadenopathy

Plain film Plain films of the neck show some prevertebral soft tissue swelling but no evidence of calcification

Ultrasound Ultrasound scanning of the neck showed reactive lymphadenopathy only

Axial & Coronal T2W MRI Neck Urgent neck MRI showed an inflammatory collection in the left prevertebral soft tissues, confined to the left longus colli muscle

MRI Neck T1W Add images in best plane showing ?3 tiny enhancing lesions Irregular thick walled fluid collection in the left longus colli muscle

MRI Neck T1+C Fat saturated T1 post contrast MRI showed a large irregular rim enhancing inflammatory mass in the prevertebral soft tissues within the left long colli muscle

Initial diagnosis Retropharyngeal abscess

Further investigations & management Surgical neck exploration No drainable abscess identified Biopsy of the post nasal space Reactive hyperplasia Commenced on IV antibiotics Remained an inpatient for 10 days

Clinical improvement and discharged home with a course of oral antibiotics

Follow-up MRI at 1 month Axial fat saturated T1 pre and post contrast demonstrates marked improvement with some mild residual enhancement in the left longus colli muscle

Longus colli tendinitis Acute calcific tendinitis of the longus colli muscle is a rare condition that causes severe neck pain (1). Calcium hydroxyapatite crystals are deposited causing acute inflammatory changes in the muscle. Benign condition that usually mimics more serious causes of acute neck pain such as retropharyngeal abscess, meningitis and infectious spondylitis (2).

Longus colli tendinitis Classic imaging findings of calcification in the prevertebral soft tissues on CT and plain film may not be present (3). Longus colli tendinitis can present with a retropharyngeal effusion/fluid collection which can mimic retropharyngeal abscess (4, 5) To our knowledge this is the first case diagnosed in a child and with a fluid collection displaying a thickened irregularly enhancing wall confined to the longus colli muscle Longus colli tendinitis is an important condition to recognise as it can be treated conservatively and usually will resolve with symptomatic treatment after 1 to 2 weeks. Early diagnosis can prevent unnecessary invasive management or investigations such as neck surgery and biopsy Longus colli tendinitis can have a range of imaging appearances and should be suspected in cases of lesions confined to the longus colli muscle Tissue from which sites? Is muscle a key target?

Longus colli tendinitis; classic imaging findings (6) Foci of amorphous calcification within the superior fibres of the longus colli tendon are typical. Non contrast enhanced CT is the imaging modality of choice. Images taken from; OFFIAH CE, HALL E. Acute calcific tendinitis of the longus colli muscle: spectrum of CT appearances and anatomical correlation. British Journal of Radiology 2009 June;82(978):e121.

Take home points Longus colli is a rare condition which can mimic serious causes of neck pain and stiffness Classic calcifications in the superior fibres of the longus colli muscle tendon may not be present The finding of a retropharyngeal fluid collection smoothly enlarging the retropharyngeal space should prompt the radiologist to search for calcifications in the longus colli tendon (4) The diagnosis should be considered when there is absence of compelling imaging or clinical evidence of acute bacterial infection (4) Early recognition can prevent unnecessary invasive surgery The condition usually settles within weeks with conservative management with anti-inflammatory medications

References 1) Estimable K, Rizk C, Pujalte GGA. A rare case of neck pain: acute longus colli calcific tendinitis in a possibly immunocompromised individual. Journal of the American Board of Family Medicine : JABFM 2015 January;28(1):146-150. (2) Shin D, Ahn C, Choi J. The Acute Calcific Prevertebral Tendinitis: Report of Two Cases. Asian Spine Journal 2010 December 1;4(2):123-127. (3) Kang C, Son ES, Kim DH, Jang H. Acute Longus Colli Tendinitis without Calcification. Journal of the Korean Orthopaedic Association 2015 June 1;50(3):264-267 (4) Eastwood JD, Hudgins PA, Malone D. Retropharyngeal effusion in acute calcific prevertebral tendinitis: diagnosis with CT and MR imaging. American Journal of Neuroradiology 1998 October 1;19(9):1789. (5) Ronak Rahmanian, Chris Diamond. Calcific Tendonitis of the Longus Colli Muscle: A Noninfectious Cause of Retropharyngeal Fluid Collection. Case reports in otolaryngology 2014;2014:286190. (5) OFFIAH CE, HALL E. Acute calcific tendinitis of the longus colli muscle: spectrum of CT appearances and anatomical correlation. British Journal of Radiology 2009 June;82(978):e121