Background: We present the anesthetic approach in the case of a baby with several malformations in face, airway and lungs (CT diagnosed), included in a syndrome confirmed after surgery: Lenz-Majewsky Hyperostotic Dwarfism (LMHD). Case Report: 40 days old infant requires urgent extramucosal pylorotomy. Arriving to operating room, some features draw our attention: low weight (2.1 kg), exophthalmos and ocular hypertelorism, sharpy upper lip, ogival palate and retrognatia. The anesthetic approach was addressed as a case of difficult airway. We performed anesthetic induction with sevoflurane and orotracheal intubation with straight shovel nu00ba 0 (Cormack II) using ETT nu00ba 2.5, without incidences. Maintenance was made with sevoflurane, high O2 rate and fentanyl, without neuromuscular relaxant. Ventilation was based on volume-controlled mode (respiratory rate from 35 to 30 breaths/min and tidal volume 4-6 ml/kg depending on CO2 levels). Just after intubation there was a drop in the end tidal values of CO2, ranging from 24-26 mmHg in manual ventilation to 0 in controlled ventilation probably due to pulmonary malformations. During surgery, SaO2 ranged between 94-99%; we decided not to use PEEP but we performed some slight manual recruitment maneuvers. Awakening developed without incidences and the baby was transferred to pediatric ICU safely. Later, pediatricians requested a genetic study that confirmed LMHD. Discussion: Clinicians should be prepared to deal with non-diagnosed syndromic patients, observing them and getting prepared for difficulties that could be found depending on suspicion. For anesthesiologists, airway, cranial and hemodynamic features are very relevant1. LMHD is a very rare syndrome caused by a de novo heterozygous mutation in phosphatidylserine synthase 1 gene with autosomal dominant pattern1; not usually diagnosed just after birth so therapeutic treatments can be necessary before diagnosis2. References: 1.Wattanasirichaigoon, D et al. Clin. Dysmorph 2004:13;137-142. 2.Baum VC et al. Anesthesia for Genetic, Metabolic and Dysmorphic Syndrome of Childhood. Philadelphia: Lippincott Williams & Wilkins; 2006. Learning points: 1-Carefully evaluate airway and plan for potential difficult management2. 2-Inhalation induction could be the safest approach in these cases. 3-Assessment of malformations is crucial for the best anesthetic management. 4-Care with the position of the patient especially if muscle-skeletal disorders are diagnosed or suspected2.