S4231 A Rare Foregut Duplication Cyst With Steatocystomatous Differentiation Presenting With Dysphagia and Vocal Cord Palsy

Introduction: Foregut duplication cysts are rare congenital anomalies that arise from the abnormal budding of the primitive foregut, which gives rise to structures of both the respiratory and upper gastrointestinal tracts. These cysts typically present in childhood and are uncommon in adults. Steatocystoma multiplex, on the other hand, is an ectodermal lesion of sebaceous gland origin. To our knowledge, this is the first reported case of a foregut duplication cyst with steatocystomatous histology, suggesting a novel embryological overlap. Case Description/Methods: A 34-year-old man presented with progressive hoarseness and intermittent dysphagia. Laryngoscopy revealed left vocal cord paralysis. Magnetic resonance imaging of the neck demonstrated a 3 cm cystic lesion in the left tracheo-esophageal groove, compressing the left recurrent laryngeal nerve and adjacent oesophagus. Surgical excision was performed. Histopathology revealed a cyst lined by cuboidal epithelium with numerous sebaceous gland nests, findings consistent with steatocystoma multiplex. The overall features supported a diagnosis of foregut duplication cyst with ectodermal differentiation. Gastrointestinal origin was favoured based on location and embryological derivation, with differential diagnoses such as bronchogenic cyst, dermoid, and branchial cleft cyst ruled out histologically and by location. Discussion: This case is notable for both its location in the foregut-derived oesophageal-tracheal axis and its never-reported histologic finding of sebaceous differentiation. The coexistence of ectodermal (sebaceous) and endodermal (foregut-derived) features suggests a unique embryological misdirection. Though duplication cysts are generally benign, their compressive potential on nearby gastrointestinal (GI) and respiratory structures, including the recurrent laryngeal nerve and oesophagus, can lead to symptoms such as vocal cord paralysis and dysphagia, warranting surgical excision. Complete resection is essential to prevent recurrence and rule out rare malignancies. This first-of-its-kind case of a foregut duplication cyst with steatocystomatous histology expands the spectrum of upper GI congenital anomalies. It underscores the need for GI clinicians to consider rare embryologic variants in cystic lesions of the neck and mediastinum, particularly when symptoms like dysphagia and hoarseness are present, and to rely on detailed histopathology for accurate diagnosis and management.