The sutures in the cranial vault are well-known, but the sutures/fissures of the skull base are much less discussed, although they can be classic origins for certain lesions. One such example is the petro-occipital suture (highlighted below in red; the contralateral suture unmarked), which, not suprisingly, lies between the occipital bone and the petrous aspect of the temporal bone.
The suture links the jugular foramen posteriorly and the foramen lacerum anteriorly.
So why is this suture important? It is a classic location where chondrosarcomas of the skull base can arise (6% of skull-based lesions). The painless, locally-invasive tumor arises from remnants of embryonal chondrocytes within the petro-occipital fissure and typically expands upward into intracranial structures.
Radiologically, a destructive mass located at this fissure (heterogeneous enhancement on post contrast T1, hyperintense on T2; chondroid calcification on CT) is highly suspicious of this diagnosis. The T1 w/ contrast image below (from Reference 2) is an example of a chondrosarcoma arising from the left petro-occipital fissure (the arrowhead demonstrates the petro-occipital fissure on the right).
Incidentally, although the molecular mechanism of eventual petro-occipital suture ossification is similar to that of the cranial vault sutures, it is unclear why it remains relatively unossified in the nonpathological state until late in adulthood.
A case report of an amyloidoma involving the petro-occipital suture has been described as well (images below). [Reference 3].
It has also been suggested that Maffuci syndrome and Ollier syndrome may be associated with intracranial chondrosarcomas arising from the petro-occipital fissure (Ref. 4).
References:
1. Balboni AL, Estenson TL, et al. "Assessing Age-Related Ossification of the Petro-Occipital Fissure: Laying the Foundation for Understanding the Clinicopathologies of the Cranial Base." The Anatomical Record Part A 282A:38–48 (2005)
2. Connor SEJ, Leung R, Natas S. "Imaging of the petrous apex: a pictorial review." The British Journal of Radiology, 81 (2008), 427–435
3. Simoens WA, van den Hauwe L, et al."Amyloidoma of the Skull Base." AJNR Am J Neuroradiol 21:1559–1562, September 2000
4. Tibbs RE, Bowles AP, Raila FA. "Maffuci's Syndrome and Intracranial Chondrosarcoma." Skull Base Surgery Vol 7, no. 1. (1997)
