Renal Cystadenocarcinoma and Nodular Dermatofibrosis (RCND)
Renal Cystadenocarcinoma and Nodular Dermatofibrosis (RCND) is a genetic disorder causing kidney, dermal and uterine cancer in German Shepherd Dog. This canine disease is equivalent to human disorder called Birt-Hogg-Dube. They share phenotypical similarities, such as firm nodules in the skin and subcutis and kidney tumors, and are suspected to share the same causative gene. However, the difference is that Birt-Hogg-Dube human patients frequently experience pneumothorax (lungs collapse) and they do not experience uterine leiomyomas, unlike in German Shepherds. Versions of the same causative mutation, except in German Shepherds and humans, have been found in rats, mice and fruit flies.
The terms ”carcinoma” and ”adenocarcinoma” are used for a condition in which cancers are formed in the epithelial tissues of skin and body organs. Adenocarcinoma is a type of cancer that forms in mucus- secreting glands throughout the body. It has an aggressive nature with a persistent tendency for metastasis. Dermatofibroma is a term used for a slowly growing benign skin nodule. Benign tumors over time may transition to malignant tumors.
Characteristics and Symptoms
Main complaints in renal Cystadenocarcinoma and Nodular Dermatofibrosis (RCND) affected German Shepherd are tumors and nodules in the skin. Generally, clinical signs can vary greatly between affected dogs, depending on age and the stage of the disease during examination. Females and males were affected equally. With aging, number of skin tumors and the uterine tumors increased, and the bilateral renal changes became more pronounced. In all examined dogs, nodular dermatofibrosis was present, while changes in the kidney region or in the abdomen were present in 60% of the dogs. Excessive thirst and fluid intake (polydipsia), fever and blood in the urine (haematuria) may be present. Behavioral changes have been recognized, in form of depression and loss of appetite. First symptoms appear around 6 to 7 years, as small, firm bumps under the surface of the skin. The bumps are most commonly located on the limbs and head. Their range is usually from 2 to mm in diameter. Histopathological examination of kidneys reveals multiple solid and cystic tumors and cysts. Both kidneys are always affected, but they vary in degree. The most frequent metastatic sites were the sternal lymph nodes, liver, lung, renal and other abdominal lymph nodes, pleura and peritoneum. Metastasis was also recorded in spleen and bronchial lymph nodes.
Most of dogs are euthanized due to severity of the disorder, while other affected dogs die naturally around 9 years of age. Main causes of natural death are renal cystadenocarcinomas and complications, such as metastasis, together with nodular dermatofibrosis and secondary skin infections.
Renal Cystadenocarcinoma and Nodular Dermatofibrosis (RCND) in German Shepherd is caused by a mutation in the gene encoding folliculin (FLCN). The gene is mapped to a canine chromosome 5. The function of the protein folliculin, encoded by these gene, is unknown.
The disorder is inherited as an autosomal dominant disorder. Homozygous and heterozygous dogs for the mutation will be affected. Homozygous puppies are most likely to die very early in gestation. Since the clinical signs develop in adult age, affected dogs are likely to be already used for breeding. Therefor it is important to be aware of the disorder prior to dog breeding, which is enabled through performance of Renal Cystadenocarcinoma and Nodular Dermatofibrosis (RCND) DNA test.
Lingaas F, Comstock KE, Kirkness EF, Sørensen A, Aarskaug T, Hitte C, Nickerson ML, Moe L, Schmidt LS, Thomas R, Breen M, Galibert F, Zbar B, Ostrander EA. (2003): A mutation in the canine BHD gene is associated with hereditary multifocal renal cystadenocarcinoma and nodular dermatofibrosis in the German Shepherd dog. Hum Mol Genet. 2003 Dec 1; 12(23):3043-53.