Commissural lip fistula

Commissural lip fistula, also known as commissural lip pit or congenital fistula of the lip commissure, is a rare congenital anomaly affecting the oral region. It is classified under congenital malformations of the lips (ICD-10: Q38.0). The condition is characterized by the presence of a small pit, sinus tract, or fistula located at or near the commissure (corner) of the mouth. These fistulae are believed to result from a developmental defect during embryogenesis, specifically involving incomplete fusion of the maxillary and mandibular processes that form the oral commissure. The condition primarily affects the orofacial structures and is typically present at birth. Clinically, commissural lip fistulae usually appear as small, often bilateral, openings at the corners of the mouth. They may be asymptomatic and discovered incidentally, or they may occasionally produce mucoid secretions from minor salivary glands that drain into the tract. In most cases, the condition is benign and does not cause significant functional impairment. However, some patients may experience cosmetic concerns, recurrent local irritation, or mild infection of the fistulous tract. Commissural lip fistulae should be distinguished from other congenital lip pits, particularly those associated with Van der Woude syndrome, which involve the lower lip and are associated with cleft lip and/or palate. Treatment, when indicated, is primarily surgical. Simple excision of the fistulous tract is the standard approach and is generally curative. Surgery may be recommended for cosmetic reasons, recurrent symptoms, or to prevent potential complications such as infection. The prognosis following surgical excision is excellent, with low recurrence rates. In asymptomatic cases, observation without intervention may be appropriate.

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