Thursday 15 March 2012

Salt and Pepper sign

The term is used to describe the speckled appearance of the tissue.
Used in many instances in radiology as well as even some pathology textbooks and journals mentions this term while describing the tissue but most commonly used while described the tissue during MRI interpretation.
* Vascular tumours
Highly vascular tumours such as a paragangliomas which contain flow void and areas of haemorrhage they are Glomus tympanicum , Glomus jugulare , pheochromocytoma and , carotid body tumour.
‘Salt' represents the hyperintensity of mass due to areas of hemorrhages in these hypervascular tumors.
‘Pepper' represents multiple black dots due to signal void of vessels.
The appearance is seen on T1 w images, may be seen on T2w images. Such lesions show ‘blooming’ low signal intensity hemosderin staining on T2*GRE, intense enhancement on post contrast due to the hyper vascularity of the mass.
* Vertebral haemangioma
A less common usage for the term is for vertebral haemangiomas which have a courser black and white dotted appearance especially on axial T2 and T1 images (salt = fat, pepper = coarsened trabeculae).
* Sjogren syndrome
The parotid gland in Sjogren's syndrome has also been described with this appearance, due to a combination of punctate regions of calcification (pepper) and fatty replacement (salt)

Glomus jugulare 
Rare, slow-growing, hypervascular, benign but locally invasive tumor.
Seen at Cp angle near jugular foramen of the temporal bone.
Represent small collections of paraganglionic tissue, derived from embryonic neuroepithelium admixed with autonomic nervous system, found in the region of the jugular bulb.
Globus jugulare is a part of group Paraganglioma, also referred to as chemodectomas or nonchromaffin paragangliomas. Paragangliomas are found at other sites also, including the middle ear (glomus tympanicum), the carotid body (carotid body tumor), and the vagus nerve in proximity to the inferior (nodosum) vagal ganglion (glomus vagale tumor, glomus intravagale tumor).
Association of glomus jugulare is reported with Pheochromocytoma, parathyroid adenoma, and thyroid carcinoma.
Histologically Glomus jugulare described as dense matrix of connective tissue among nerve fascicles.
Expand within the temporal bone via the pathways of least resistance such as air cells, vascular lumens, skull base foramina and the eustachian tube. Spares the ossicular chain.
Often noted as an incidental finding. May go unnoticed due  to non specific and insidious onset symptoms. Predominantly occur in female, common during their fifth and sixth decades of life, more common on the left side.
A 40 yo female presented with hydrocephalus due to mass effect of a Hemangioblastoma (H) at the floor of posterior fossa. The Glomus jugulare tumor (G) with typical salt and pepper appearance on T1w images noted as an incidental finding.
Multicentric tumors are known in ~ 3-10% of sporadic cases and in 25-50% of familial cases.
Metastases from glomus tumors occur in approximately 4% of cases, includes lung, lymph nodes, liver, vertebrae, ribs, and spleen.
CE MRI is investigation of choice, characteristic salt and pepper appearance on T1 and T2-weighted images.

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