¹Department of Diagnostic Radiology, Karolinska Sjukhuset, Stockholm, Sweden

Correspondence: Dr N Lindvall, Department of Diagnostic Radiology, Karolinska Sjukhuset, Stockholm, Sweden.

Abstract

Necrosis of the renal papillae was first described by von Friedreich [1] in 1877, and the radiologic appearances were first described by Praetorius [2] in 1937. Further radiologic details were published by Günther [3, 4], Lagergren and Lindvall [5], Lindvall [6], and Hare and Poynter [7].

Necrosis of a papilla will first result in a local disturbance in function and a swelling of the papilla, which later shrinks irregularly. The fornices of the calyx become widened. The necrotic papilla may then either be detached, and a cavity is formed, or the papilla may remain attached (in situ). In the latter case, calcium deposits may occur in the necrotic portion. When detached, the necrotic tissue may either remain in the cavity, shrink and be absorbed, or it may be passed in the urine, whole or in fragments. Sometimes the necrotic tissue may form the nucleus of a calculus. The necrotic changes never encroach upon the cortex or the columns of Bertin.

Günther [4] differentiated between two types of necrosis with detachment: the papillary form, where the whole papilla or a greater part of the medulla was necrotized, and the medullary form, where only the central part of the papilla was necrotized. As these names indicate different degrees of necrosis, and are confusing, Hare and Poynter [7] suggested a more appropriate nomenclature: total papillary necrosis (TPN) instead of papillary necrosis (Fig. 1), and partial papillary necrosis (PPN) instead of medullary necrosis (Fig. 2). They also suggested the name necrosis in situ (NIS) for those instances where there is no detachment of the necrotic papilla (Fig. 3). As this nomenclature is more adequate than that of Günther [4], I will use it here.