Bifid Ribs

Bifid Rib Clinical Features:

• Bifid rib is usually unilateral.
• May occur in isolation.
• Bifid ribs are usually asymptomatic.
• May also found with multi-system malformations.
• They often discovered incidentally by chest x-ray.

Clinical Assessment:

• Examine the mouth & skin carefully.
• Physical findings such as odontogenic cysts, subcutaneous calcifications, & palmar pits should prompt more extensive radiological / radiological investigations.
• With normal physical examination, & asymptomatic patient, further radiological assessment gives a low yield for abnormalities.

Clinical Associations:

• Gorlin-Goltz (Basal cell nevus) syndrome (65-70% of patients) [2,10]
• Job's syndrome [3]
• Kindler syndrome [4]
• Malignancy in childhood (esp neuroblastoma) [5]

Complications:

• Asymptomatic (usually)
• Intercostal nerve entrapment
• Musculoskeletal pain
• Thoracic outlet syndrome [6]

Epidemiology:

• Prevalence of bifid rib ~ 0.15% to 3.4% (~ 2%). [1]
• Up to 20% of all congenital rib anomalies. [1]
• Bifid ribs occur in up to 8.4% of Samoans. [8]
• Bifid ribs on chest Xray occur in 2.8% of Koreans. [9]

Morphological Patterns:

• Two distinct morphological patterns. [7]
• 1) - long and slender (fissured) bifid spaces, with the bifid rib appearing as a two-pronged fork (fork type). [7]
• 2) - more rounded bifid spaces (hole type). [7]

Pathophysiology:

• Ribs originate from the mesoderm.
• Bifid ribs may therefore be associated with other mesodermal abnormalities.
• Look specifically for malformations in other organs of mesodermal origin, i.e. heart & kidneys. [1]

Prognosis:

• That of underlying cause.
• There is little information in the literature about the clinical significance of bifid ribs.

References:

• [1] - Charles I, Scott J. Pectoral girdle, spine, ribs, and pelvic girdle. In: Stevenson RE, Hall JG, Goodmann RM, eds. Human Malformations and Related Anomalies, vol 2. Oxford University Press: New York, 1993:655–697.
• [2] - Rai S, Gauba K. Jaw cyst-basal cell nevus-bifid rib syndrome: a case report. J Indian Soc Pedod Prev Dent 2007; 25:137–139.
• [3] - Freeman AF, Holland SM. The hyper-IgE syndromes. Immunol Allergy Clin North Am 2008; 28:277–291.
• [4] - Sharma RC, Mahajan V, Sharma NL, Sharma AK. Kindler syndrome. Int J Dermatol 2003; 42:727–732.
• [5] - Schumacher R, Mai A, Gutjahr P. Association of rib anomalies and malignancy in childhood. Eur J Pediatr. 1992;151:432–434. [PubMed]
• [6] - K. Cağli. Thoracic outlet syndrome in an adolescent with bilateral bifid ribs. Clin Anat. 2006 Sep;19(6):558-60.
• [7] - Wu-Chul Song, Sang-Hyun Kim, Dae-Kyoon Park, and Ki-Seok Koh. Bifid Rib: Anatomical Considerations in Three Cases. Yonsei Med J. 2009 April 30; 50(2): 300–303
• [8] - Martin EJ. Incidence of bifidity and related rib abnormalities in Samoans. Am J Phys Anthropol. 1960;18:179–187.
• [9] - Lim CK, Lee KW, Bin JC, Rhee BC. Congenital anomalies of the ribs. J Korean Soc Plast Reconstr Surg. 1982;18:487–495.
• [10] - Bitar GJ, Herman CK, Dahman MI, Hoard MA. Basal Cell Nevus Syndrome: Guidelines for Early Detection. Am Fam Physician. 2002 Jun 15;65(12):2501-2505.

Image: Bifid Rib (CT Chest)

Image Credit: Dr Frank Gaillard (radpod.org) (cc)

Tags: Bifid Rib - Gorlin-Goltz Syndrome - Job Syndrome - Kindler Syndrome - Mesoderm - Neuroblastoma - Rib - Samoan
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