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At a glance

A most often asymptomatic, sporadically occurring disorder resulting in cystic dilatation of the collecting tubules of the kidneys. Complications include urinary tract infections, hematuria, nephrocalcinosis, and rarely renal dysfunction.

Synonyms

Lenarduzzi-Cacchi-Ricci Disease; Medullary Sponge Kidney (MSK); Precaliceal Canalicular Ectasia; Ricci-Cacchi Syndrome.

History

The first description (an abstract) is credited to the Italian radiologist Guerrino Lenarduzzi (1902-1985) who described the disorder in 1939 and coined the term “sponge kidney.” However, most often the disorder only bears the names of Roberto Cacchi, an Italian urologist, and Vincenzo Ricci, an Italian otorhinolaryngologist (at the time of the publication he worked as an assistant in the pathology department) who described the disorder in 1948 (they all worked at the University Hospital in Padua, Italy).

Incidence

Up to one in 200 urographies may show signs of Cacchi-Ricci Disease (CRD). The actual incidence in the general population is not exactly known (because it may be asymptomatic), but the estimated incidence ranges from 1:5,000-10,000. CRD has been found in 13% of 800 patients with calcium urolithiasis, with a higher frequency in women (19%) than in men (12%). However, in most series, men are more frequently affected than women, but morbidity seems to be higher in females. No racial predilection has been reported.

Genetic inheritance

Most cases are sporadic, although a few familial cases (with reduced penetrance and variable expressivity) have been described and estimated to account for around 5% of CRD cases. However, due to the fact that CRD may be asymptomatic or present with minor symptoms only, familial CRD might go undiagnosed or misdiagnosed, thus familial occurrence may be more common (a recent study quoted up to 50% of cases) than previously thought. Autosomal dominant inherited CRD 1 is caused by mutations in the transmembrane mucin 1 (MUC1) gene, which has been mapped to chromosome 1q22, while autosomal dominant inherited CRD 2 is caused by a heterozygous mutation in the Uromodulin (UMOD) gene located on chromosome 16p12. There is some emerging research that suggests that mutations in the REarranged during Transfection (RET) proto-oncogene (on chromosome 10q11.210) and the Glial cell line-Derived Neurotrophic Factor (GDNF) gene (on chromosome 5p13.2) play a role in the development of CRD and occasional associated anomalies.

Pathophysiology

The exact pathophysiology remains unknown. However, most researchers consider CRD to be a developmental defect affecting the formation of the collecting tubules, while others consider it a primary progressive degeneration of the collecting tubules manifesting later on in life. Some experts also consider the defect in the distal acidification of urine to play a crucial role in CRD that influences bone mineralization, hypercalciuria, hypocitraturia, and kidney stone formation. The kidney size is usually normal or slightly enlarged. Histopathologic examination reveals cystic dilatation of the renal medullary collecting ducts (diameter 1-8 ...

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