Mandibuloacral dysplasia type B in an infant: a rare progeroid genodermatosis.

ReportofaCase |A5-month-oldboyofnon-consanguineousparents presented with congenital brown pigmentation on his ankles that progressed to the knees, shins, andwrists. Born at 35weeks’ gestation via cesarean delivery, he had facial asymmetry and leg contractures initially attributed to breech positioning in utero. He had poor weight gain but normal vision andhearing. At age 3months, he underwent a skeletal survey that revealedmandibular hypoplasia andosseous abnormalities of the clavicles, humeri, and tibia. Results of a chromosomal screen were negative. No known relations, including 2 paternal half-siblings, had similar findings. Physical examination showed a cheerful boy withmicrognathia, a small nose, prominent eyes, large, open fontanelles, and thin, contracted lowerextremities (Figure,A).Nonindurated light brown patches were present on the wrists, bilateral tibias, and ankles. The clinical and radiologic findings suggestedaprogeroid laminopathy.Anatypical progeroid syndrome was considered, but the patient’s young age favored MAD type B. Analysis of theZMPSTE24geneconfirmedMADtypeB, revealing a compound heterozygousmutation that combined a missense mutation (Asn265Ser) inherited from the patient’s mother with a nonsense mutation (Leu362Phefs*19) inherited from his father. At age 10 months, his skin was notably thinner, appearingmore tautly stretchedover increasingly lipoatrophic lower legs (Figure, B). Acro-osteolysis was becoming apparentwith noticeably shortened distal phalanges and broad, hypoplastic fingernails. His diagnosis prompted nephrologic and endocrinologic consultations and management for long-term morbidity.