Buschke-Ollendorff syndrome presenting as a painful nodule

BOS: Buschke-Ollendorff syndrome INTRODUCTION First reported in 1928, Buschke-Ollendorff syndrome (BOS) is an autosomal dominant genodermatosis with high penetrance and variable expressivity. It is characterized by skin-colored or yellow smooth papules, plaques, and nodules up to 2 cm consisting of elastomas or collagenomas, known as dermatofibrosis lenticularis disseminata. This syndrome also has nearly pathognomonic radiographic findings of 1to 10-mm spherical, radiopaque osteosclerotic foci with uneven contours at the epiphysis and metaphysis of the long bones, pelvis, carpi, and tarsi, with rare inclusion of the spine. These foci are known as osteopoikilosis or osteopathia condensans. This syndrome may have cutaneous manifestations during early childhood, with most findings developing by puberty. Radiographically, it generally manifests during adolescence and appears most commonly in the phalanges, carpi, and metacarpi but may appear as early as age 2. BOS is present equally in males and females, with an estimated prevalence of 1:20,000 in the general population. Patients may only have bone or dermatologic findings, but dermatologic manifestations are more commonly present and may include variations of grouped papules and nodules. Debilitating symptoms are rare, but radiographic findings may be confused for primary osteoblastic or metastatic disease. We present a case of BOS incidentally diagnosed in a 20-year-old white man, with both radiologic and cutaneous findings discovered after complaints of a painful enlarging nodule on the right lower extremity.