Sternocostoclavicular hyperostosis and the impact of diagnostic delay: comment on the article by Van der Kloot et al.

We read with great interest the article by van der Kloot et al, recently published in Arthritis Care & Research, regarding the diagnostic delay in sternocostoclavicular hyperostosis (SCCH) (1). We fully agree with van der Kloot et al, both on the detrimental consequences of a delayed diagnosis of SCCH on various aspects of the quality of life, and on the need for greater awareness of the anterior chest wall (ACW) pain syndromes by the general practitioners. In 1987, Kahn suggested the acronym SAPHO (which stands for synovitis, acne, pustulosis, hyperostosis, and osteitis syndrome) in order to unify various conditions characterized mainly by osteitis/hyperostotic lesions of the ACW (2). Therefore, SAPHO syndrome can be considered a “useful concept” that unifies several disorders sharing some clinical, radiologic, and pathologic characteristics, especially osteitis/hyperostotic lesions of the ACW. This means that the understanding of SAPHO syndrome is also very important in musculoskeletal radiology, since such awareness could facilitate the differentiation from other entities that produce similar radiographic findings but have different prognoses and treatments, such as osteomyelitis, Ewing’s sarcoma, metastasis, and Paget’s disease of bone (3). Our work, previously published in Arthritis Care & Research, indicated that SCCH represents the first osteoarticular symptom in 70% of patients with SAPHO syndrome followed in our tertiary referral rheumatology unit (4). In our experience, the diagnostic delay led to the execution of inappropriate investigations and the prescription of inadequate treatment. In addition, we reported that 19 patients had a history of several admissions to the emergency room for a suspected acute cardiac event. The median ages, both at the time of the first osteoarticular symptom of the disease and at the time of the diagnosis, are shown in Table 1. It is also worth recalling that skin lesions may not be accounted for when they are either episodic or appear after bone lesions. We would like to point out that SCCH is the typical target of SAPHO syndrome, representing the mainstay of the diagnosis, but it is not pathognomonic of the disease. A similar involvement may also be seen in spondylarthropathies, especially in psoriatic arthritis (PsA). In PsA, however, SCCH is more frequently a late complication of the disease and does not usually involve the medial end of the claviculae. We think osteitis/hyperostosis of this difficult anatomic site should be regarded as a distinguishing feature of SAPHO syndrome. In conclusion, we agree that diagnostic delays are relevant, but they could be due to the fact that the first referral of these patients is usually not to a rheumatologist. Therefore we firmly hope, as already suggested (4), that other specialists such as dermatologists, emergency room doctors, and general practitioners have greater confidence in recognizing this condition.