Age / Sex : 27 / M

Chief complaint :

Bilateral knee pain, thumb nail deformity

What is your impression?

Two weeks later, you can see the final diagonosis with a brief discussion of this case (Please submit only one answer).

Courtesy : Hee-Dong Chae, Seoul National University Hospital

Discussion

Answer:  

Nail-patella syndrome (hereditary onycho-osteodysplasia, Turner-Keiser syndrome, Fong disease)

Findings:

Aplasia of bilateral patellae

Dysplasia of the capitellum and radial head with radial head subluxation, more pronounced in the right elbow

Differential Diagnosis:

Small patella syndrome, Trisomy 8, Coffin-Siris syndrome, Kuskokwin syndrome

Discussion:

Nail-patella syndrome (NPS) is a rare hereditary disorder known by many other names, including hereditary onycho-osteodysplasia (HOOD), Turner-Keiser syndrome, and Fong disease. It is characterized by a classic tetrad of nail hypoplasia or aplasia, aplastic or hypoplastic patellae, elbow dysplasia, and the presence of iliac horns.

Nail changes are the most constant feature of NPS, with the thumbs most severely affected. Nails may be absent, hypoplastic, or dystrophic; ridged longitudinally or horizontally; pitted; discolored; separated into two halves by a longitudinal cleft. Patellar abnormalities are present in >90% of cases and include aplasia or, more frequently, patellar hypoplasia. Elbow abnormalities may include dysplasia of radial heads, lateral epicondyles, and capitula with recurrent displacement of the radial heads. Iliac horns, which are pathognomonic for NPS, are bilateral, conical, osseous excrescences that project posterolaterally from the posterior ilia.

Besides physical manifestations, there is also an association with open-angle glaucoma and progressive nephropathy. Clinical manifestations are most frequently seen in the second and third decades of life. There is no cure for NPS, and treatment is directed towards addressing the various orthopedic and nonorthopedic manifestations of the disorder.

References:

1. West JA, Louis TH, editors. Radiographic findings in the nail-patella syndrome. Baylor University Medical Center Proceedings; 2015: Taylor & Francis.


2. Tuncbilek N, Karakas H, Okten O. Imaging of nail-patella syndrome. Hong Kong Med J. 2005;11(2):116-8.