Pai syndrome is a rare disorder first described by Pai et al. in 1987 in a female newborn that presented with clefting of the upper lip, nasal skin polyps, and midline lipoma of the brain [1]. As an isolated finding, median clefting of the upper lip is rare. However, this condition may be related to several syndromes [4]. The nasal polyps are considered the hallmark of Pai syndrome and the most common site of presentation is the nasal septum that gives rise to polyps arising through the nostrils. The columella is the second most common site; rare locations are the dorsum/bridge and tip of the nose [5]. Usually, these polyps are hamartomas (lipomas and myolipomas) [5, 6].

After the original description of this syndrome, several cases characterized by median facial cleft without cleft palate, nasal or facial polyps, or brain interhemispheric lipomas have been reported. Therefore, minimum diagnostic criteria for Pai syndrome have been established: one or more hamartomatous nasal polyps plus a median cleft lip (with or without cleft alveolus or palate) and/or mid-anterior alveolar process congenital polyp [5]. As pericallosal lipoma was reported in 85 % of the cases that underwent brain imaging, this feature has also been proposed as an additional criterion [3].

Interhemispheric/pericallosal lipomas have typical ultrasound features that make them very easy to identify during prenatal ultrasound in the majority of cases [7]. As there is no adipose tissue in the brain, lipomas of the central nervous system are presumed to arise from the primitive meninx descending into the interhemispheric fissure during cleavage of the prosencephalic vesicle [8]. At this location, the lipoma may interfere with corpus callosum development [7]; therefore, complete/partial agenesis or hypoplasia of the corpus callosum is a frequently associated finding [5, 7, 9]. Other developmental anomalies of the craniofacial region that are included in the clinical spectrum of Pai syndrome are bifid nose, bifid uvula, double frenulum, midline sinus, median alveolar cleft, and ocular hypertelorism. Occasionally, ophthalmic abnormalities of the iris and cornea, like coloboma, microcornea, or lenticonus, have been also reported [2, 3, 8]. DeMyer [10] stated that median cleft of the upper lip is associated with orbital hypertelorism and five other facial defects: V-shaped frontal hairline, cranium bifidum occultum, primary telecanthus, median cleft of the premaxilla, and median cleft palate.