Diaphyseal Dysplasias

We'll be dealing with two possibly related disorders: Progressive diaphyseal dysplasia (Camurati-Engelmann disease, Engelmann disease) and hereditary multiple diaphyseal sclerosis (Ribbing disease, shown above). The arguments for and against the relatedness of these disorders are not convincing one way or the other and will not be discussed.

Both are disorders of intramembranous ossification, primarily affecting the diaphysis and sparing the metaphysis and epiphysis, which are formed by endochondral ossification. Both conditions manifest radiographically as periosteal and endosteal hyperostosis of the long bones. Bone scintigraphy can be positive in both. The clinical and imaging presentations diverge after this:

	Camurati-Engelmann	Ribbing
Patient age	Children	Young adults to middle aged
Disease course	Progression or regression	Slow progression followed by stabilization
Symptoms	Waddling gait, bone pain, myopathy, and weakness	Bone pain in the affected extremities
Patient appearance	Elongated long bones (Marfanoid)	Non-Marfanoid
Distribution	Bilateral and symmetric	Unilateral or asymmetrically and asynchronously bilateral (usually lower extremities)
Skull base involvement	Sometimes	No

Other conditions can mimic these diaphyseal dysplasias. Medullary osteosclerosis, like Camurati-Engelmann and Ribbing diseases can present radiographically as increased bone formation within the medullary cavity of the long bones of the lower extremities. Like Ribbing disease, the onset is usually in adulthood. Unlike the two diaphyseal dysplasias that are the subject of this post, the sclerosis in medullary osteosclerosis is limited to the medullary space, with minimal or no cortical thickening.

Melorheostosis can also present with both peri- and endosteal hyperostosis, but the endosteal hyperostosis, if present, is usually seen in later stages of the disease and is less advanced than the characteristic periosteal hyperostosis.

Finally, Erdheim-Chester disease may have cortical thickening, narrowing of the medullary cavity, sparing of the epiphyses, and a symmetric lower extremity dominant distribution. In addition to the above, radiographs of patients with Erdheim-Chester disease can show bone infarctions and periostitis.

The images above from a 50-year-old man show asymmetric right lower extremity endosteal and mild periosteal hyperostosis. The skull is normal. The age, skeletal distribution, and skull findings suggest Ribbing disease. Mild periosteal sclerosis is seen, helping differentiate this case from medullary osteosclerosis.

Eponym: The Ribbing in Ribbing disease is not a gerund, but is the last name of the Swedish radiologist (Seved Ribbing) who described the condition in 1949.

References

• Ihde LL, Forrester DM, Gottsegen CJ, Masih S, Patel DB, Vachon LA, White EA, Matcuk GR Jr. Sclerosing bone dysplasias: review and differentiation from other causes of osteosclerosis. Radiographics. 2011 Nov;31(7):1865-82.
• Ribbing S. Hereditary, multiple, diaphyseal sclerosis. Acta radiol. 1949 Jun 30;31(5-6):522-36.
• Seeger LL, Hewel KC, Yao L, Gold RH, Mirra JM, Chandnani VP, Eckardt JJ. Ribbing disease (multiple diaphyseal sclerosis): imaging and differential diagnosis. AJR Am J Roentgenol. 1996 Sep;167(3):689-94.
• Shier CK, Krasicky GA, Ellis BI, Kottamasu SR. Ribbing's disease: radiographic-scintigraphic correlation and comparative analysis with Engelmann's disease. J Nucl Med. 1987 Feb;28(2):244-8.
• Ziran N, Hill S, Wright ME, Kovacs J, Robey PG, Wientroub S, Collins MT. Ribbing disease: radiographic and biochemical characterization, lack of response to pamidronate. Skeletal Radiol. 2002 Dec;31(12):714-9.