Acetabular dysplasia associated with intra-articular lipomatous lesions in proteus syndrome. A case report

Clinical Phenotype and Bone Biopsy Characteristics in a Child with Proteus Syndrome

Proteus syndrome is a rare genetic disorder, which is characterized by progressive, segmental, or patchy overgrowth of diverse tissues of all germ layers, including the skeleton. Here, we present a 9-year-old girl with a somatic-activating mutation (c.49G > A; p.Glu17Lys) in AKT1 gene in a mosaic status typical for Proteus syndrome. She presented with hemihypertrophy of the right lower limb and a "moccasin" lesion among others. A transiliac bone biopsy was analyzed for bone histology/histomorphometry as well as bone mineralization density distribution (BMDD) and osteocyte lacunae sections (OLS) characteristics based on quantitative backscattered electron imaging. Bone histomorphometry revealed highly increased mineralizing surface (Z-score + 2.3) and mineral apposition rate (Z-score + 19.3), no osteoclasts (Z-score - 2.1), and an increased amount of primary bone in the external cortex. BMDD abnormalities included a decreased mode calcium concentration in cancellous bone (Z-score - 1.7) and an increased percentage of highly mineralized cortical bone area (Z-score + 2.4) compared to reference. OLS characteristics showed several differences compared to reference data; among them, there were the highly increased OLS-porosity, OLS-area, and OLS-perimeter on the external cortex (Z-scores + 6.8, + 4.4 and 5.4, respectively). Our findings suggest that increased bone formation reduced matrix mineralization in cancellous bone while the enhanced amount of primary bone in the external cortex increased the portion of highly mineralized cortical bone and caused OLS-characteristics abnormalities. Our results indicate further that remodeling of primary bone might be disturbed or delayed in agreement with the decreased number of osteoclasts observed in this child with Proteus syndrome.

Thoracolumbar scoliosis in a patient with Proteus syndrome: a case report and literature review

The Proteus syndrome (PS) is a complex and rare congenital hamartomatous condition with a wide range of malformations. Little is reported about spinal deformity associated with this syndrome. This study presents a case of scoliosis occurring in the setting of PS and explores the possible mechanisms between the 2 diseases. The patient is a 17-year-old Chinese female with scoliosis and hemihypertrophy of the right upper and lower extremity as well as exostosis of the right lower leg joint including the hip, knee, ankle, and toes. These manifestations were suggestive of PS. She underwent a posterior correction at thoracic 2-lumbar 4 (T5-L4) levels, using the Moss-SI spinal system. At 3-month follow-ups, the patient was clinically pain free and well balanced. Plain radiographs showed solid spine fusion with no loss of deformity correction. The severity of scoliosis in PS is progressively aggravated and the correction of the extensive spinal deformities is generally difficult. Therefore, early diagnosis is required for adequate interdisciplinary treatment.