Phantom calyx is a calyx which fails to fill with contrast admist a well opacified remainder of pyelocalyceal system. It refers to an intrarenal process which has infilterated and caused obliteration of the involved collecting system element.
It may be seen in:
- tumour: especially transitional cell carcinoma of the renal pelvis.
- renal tuberculosis
- acute pyelonephritis
- renal calculus
- renal ischaemia
- renal trauma
- congenital anomaly
- renal contusion
- technical underfilling
If the calyx is dilated and filled with tumour (but still visible) then it is referred to as an oncocalyx.
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