| INTRODUC TI ONBardet-Biedl syndrome (BBS) is a rare, autosomal recessive ciliopathy with heterogenous, multisystem presentations. BBS affects fewer than 20 000 individuals in the United States and has been associated with mutations in more than 20 distinct genes. Genes involved in BBS encode proteins that play an integral role in ciliary biogenesis and trafficking; mutations result in ciliary dysgenesis and dysfunction. 1 Clinical presentation of BBS is variable. Primary features are rodcone dystrophy, postaxial polydactyly, obesity, reduced intelligence, renal dysfunction, and hypogonadism. Secondary features are numerous and include hepatic fibrosis, diabetes mellitus, hypercholesterolemia, reproductive abnormalities, short stature, speech defects, developmental delay, hearing loss, dental abnormalities, psychiatric disturbances, hypertension, cardiovascular anomalies, ataxia, and craniofacial dysmorphism. Diagnostic criteria for BBS are based on the presence of either 4 primary features or 3 primary and 2 secondary features. 2 Cutaneous features are not classically associated with BBS, although the mouse model for the syndrome displays abnormalities in hair growth and epidermal differentiation. 3 Herein, we present the first case of linear porokeratosis (LP) in a patient with Bardet-Biedl syndrome.
| C A S E REP ORTA 17-year-old boy with BBS (rod-cone dystrophy, scoliosis, hepatic fibrosis, and morbid obesity) and associated stage III chronic kidney disease (CKD) (awaiting transplant) presented to clinic with complaints of a hyperpigmented rash on the left trunk and left upper extremity. The rash developed at the age of 7 years and has remained asymptomatic since its appearance. Family history was negative for both BBS and similar cutaneous findings. Examination of the skin revealed multiple red-to-brown, annular, thin papular lesions with an atrophic center and hyperkeratotic rim in a Blaschkoid distribution on the left back, left chest, and left ventral arm (Figure 1). Physical examination was also notable for acanthosis nigricans on the bilateral dorsal hands and venous stasis with lichenification of the bilateral lower extremities. Differential diagnosis included LP, lichen striatus, and inflammatory linear verrucous epidermal nevus. A 4 mm punch biopsy was performed on a lesion from the chest. On histology, the lesion showed nonspecific inflammatory infiltrate, acanthosis, pigment incontinence, and focal cornoid lamella consistent with a diagnosis of LP (Figure 2). Abstract This case report presents a 17-year-old boy with Bardet-Biedl syndrome (BBS) and a long-standing hyperpigmented eruption on the left trunk and upper extremity, clinically and histologically consistent with linear porokeratosis (LP). BBS patients frequently require solid organ transplant, and subsequent immunosuppression places them at especially high risk for malignant transformation of premalignant skin lesions such as LP. Although BBS affects multiple organ systems, there are only a handful of case reports detailing associated cuta...
