Rib anomalies – A case and an overview of the literature 195 Klinični pRimeR id 1506 nevrobiologija Zdrav Vestn | maj – junij 2017 | l etnik 86 Klinični primer 1 Clinical Institute of Radiology, University Medical Centre Ljubljana, Ljubljana 2 General Hospital Novo mesto, Novo mesto Korespondenca/ Correspondence: igor Kocijančič, e: igor.koc@kclj.si Ključne besede: intratorakalno rebro; anomalije reber; kongenitalne anomalije; rentgenoram; računalniška tomografija Key words: intrathoracic rib; rib anomalies; congenital anomaly; radiograph; computed tomography Citirajte kot/Cite as: Zdrav Vestn. 2017; 86:195–98. prispelo: 14. 3. 2016 Sprejeto: 9. 3. 2017 Rib anomalies – A case and an overview of the literature Razvojne anomalije reber – Primer diagnosticiranja in pregled literature igor Kocijančič, 1 Andraž Zupan, 1 peter Slak 2 Abstract Anatomic rib variants (numeric and structural) are reported to occur in less than 2 % of the general population and are rarely of any clinical significance. Frequently noticed developmental rib anoma- lies include fused and bifid ribs, cervical ribs and rib dysplasia. Occasionally they can cause problems when interpreting chest radiographs, therefore it is important for radiologists to be familiar with them and consider rib variants in differential diagnosis. The following case report presents an 88-year old female with a left bifid intrathoracic rib. Izvleček Anatomske razvojne različice reber (številčne in strukturne) prizadenejo manj kot 2 % populacije in so le redko klinično pomembne. Najpogosteje opažene razvojne različice so zraščena in razcepljena rebra, vratna rebra in displazije reber. Spremembe lahko povzročajo težave pri oceni rentgenograma pljuč, zato je za radiologe pomembno, da jih poznajo in vključijo v diferencialno diagnozo. Prikazani primer obravnava 88-letno bolnico z ugotovljenim levim razcepljenim intratorakalnim rebrom. 1 Introduction Anatomic rib variants (numeric and structural) are reported to occur in less than 2 % of the general population and are rarely of any clinical significan- ce (1,2). Intrathoracic rib is one of the ra- rest rib anomalies, with only around 50 cases reported in English literature since Lutz first noted it in 1947  (1-6). The ori- gin of intrathoracic rib might be the rib itself or the vertebra. Additionally, there might be a combination of intrathoracic rib and vertebral anomalies. Patients are usually asymptomatic and the intrathoracic rib is usually dia- gnosed as an additional finding at chest radiography (1). 2 Case report An 88-year-old female was admitted to our hospital with acute cardioembolic stroke and with symptoms of upper re- spiratory tract infection and cough. She had a history of chronic hypertension, atrial fibrillation, glaucoma, osteoporo- sis and stent in the right internal carotid artery. The neurologic examination revealed dysarthria and left hemiparesis. Labora- 196 Zdrav Vestn | maj – junij 2017 | l etnik 86 neVR obiologij A Figure 1: A chest radiography. Anteroposterior view demonstrating vertical bone structure joining the third rib posteriorly on the left side. progressive reduction of the craniocaudal diameter of the structure is noticed. Figure 2: Axial CT demonstrated an extrapleural bone structure in the left hemithorax. tory tests revealed an elevated C-reactive protein (CRP). A chest radiograph (Figure 1) was performed at the emergency department and a left lower lobe consolidation was suspected. There was also a vertically oriented structure similar in density to adjacent bone, located in the upper and middle thirds of the left hemithorax, with progressive craniocaudal reduction. This finding was consistent with a bifid intrathoracic rib. The patient was given antihyperten- sive drugs and anticoagulation therapy with dabigatran. Pneumonia was treated for 10 days with Amoxicillin/clavulanic acid. The patient had undergone repeated computed tomography (CT) of the brain and CT angiography (CTA) for quantifi- cation of carotid artery stenosis (Figures 2 and 3). Head CT showed demarcated infarction in right basal ganglia region, CTA showed stent in the right internal carotid artery and 70 % stenosis of the left internal carotid artery. On CTA images we were able to bet- ter determine the origin and extension of the vertical bone structure described on the chest radiograph and we also ru- led out lung parenchyma lesion or other pulmonary complications related to the structure. A bifid intrathoracic rib that originated from the posterior arch of the third rib on the left side was diagnosed. It was vertically orientated and extended caudally along the posterior chest wall, extra pleural and not in contact with lung parenchyma. After 1 month the patient recovered and was discharged to home care. 3 Discussion An intrathoracic rib usually presents as an isolated incidental finding with either a normal rib, an additional acces- Rib anomalies – A case and an overview of the literature 197 Klinični pRimeR Figure 3: CT 3D reconstruction shows left bifid intrathoracic rib of the third rib. sory rib or prolonged arm of a bifid rib with anomalous location inside the tho- racic cavity  (3). It may originate from incomplete fusion between the cranial and caudal processes of sclerotome se- gments in the course of embryogenesis between the fourth and sixth week of fetal development. By one hypothesis, defects in gene expression could also be the causative factor in overall patient’s picture (1,3,4). Morphological structure as well as shape of the intrathoracic rib is nor- mal. It is usually described as unilateral, right-sided incidental finding betwe- en the third and eighth rib with no sex predilection. There may be increased extrapleural fat or other soft tissue po- sitioned alongside the anomalous rib to compensate for depressed deformi- ty of the chest wall  (3,5). Roughly 30 % of them are reported in children (1,5,6). Although the chest radiograph is usually the first radiological modality in the di- agnosis of intrathoracic rib, it can easily be missed or mistaken for other patho- logic formations inside the thoracic cage, either a pleural lesion, consolidation of lung parenchyma, chest drain or other bony lesion  (2,5,6). Patients are usually asymptomatic with possibility of slight chest pain, dyspnea and hemoptysis. Ad- hesions between different organs and intrathoracic rib are the main reason for symptoms to occur  (2,3,5,7). In the event of chest trauma there is a strong correlation with the risk of pulmonary injury (2). The introduction of spiral CT scan is of vital importance for definite identification and evaluation of this rare rib anomaly to avoid any other additio- nal future diagnostics or procedures. Kamamo et al. published the first clas- sification of intrathoracic ribs in 2006 (Table 1)  (6). In 2013 Mahajan et al. wrote in his case report that out of 50 cases of intrahoracic ribs in the published lite- rature only three were classified as type II  (5). To our knowledge, the presented case is the fourth case of type II intratho- racic rib. Our case is similar to the case reported by Carvalho and Lopes in 2012, but we did not perform thoracic CT scan for better evaluation of the rib. T able 1: Kamamo et al. classification of intrathoracic ribs. i-a extra normal rib originating from vertebral body i-b Supernumerary intrathoracic rib originating from a portion of rib next to vertebral body ii intrathoracic rib originating from a bifid rib iii Rib depressed inside the thoracic cavity 198 Zdrav Vestn | maj – junij 2017 | l etnik 86 neVR obiologij A 4 Conclusions In conclusion, our case is a rare pre- sentation of an intrathoracic rib, which must be considered as a normal finding and in most cases there is no need for further diagnostic procedure. References 1. Basarslan F, Bayarogulları H, Tutanc M, Arica V, Yilmaz C, Davran R. Intrathoracic rib associated with pulmonary collapse in a pediatric patient. Iran J Radiol. 2012 Nov;9(4):220–2. 2. Carvalho FHG, Lopes GP . Intrathoracic rib: a case report. Radiol Bras. 2012 Mar/Abr;45(2):121–2. 3. Bottosso N, Ghaye B. Bifid intrathoracic rib, JBR- -BTR. 2014 Oct;91(3):86–7. 4. Aoyama H, Mizutani-Koseki Y, Koseki H. Three developmental compartments involved in rib for- mation. Int J Dev Biol. 2005;49:325–33. 5. Mahajan PS, Hasan IA, Ahamad N, Al Moosawi NM. A unique case of left second supernume- rary and left third bifid intrathoracic ribs with block vertebrae and hypoplastic left lung. Case Reports in Radiology [Internet]. 2013. Available from: http://www.hindawi.com/journals/cri- ra/2013/620120/cta/. 6. Kamano H, Ishihama T, Ishihama H, Kubota Y , Ta- naka T, Satoh K. Bifid intrathoracic rib: a case re- port and classification of intrathoracic ribs. Intern Med. 2006;45(9):627–30. 7. Laufer L, Schulman H, Hertzanu Y. Intrathoracic rib demonstrated by helical CT with three-dimen- sional reconstruction. Eur Radiol. 1999;9:60–1.