What are the clinical presentation, diagnosis, and treatment options for a young adult with a dermoid cyst of gastric origin?

Dermoid Cysts of Gastric Origin in Young Adults

Critical Clarification

Dermoid cysts of true gastric origin are exceedingly rare and essentially do not occur as a recognized clinical entity in young adults. The evidence base addresses ovarian dermoid cysts (mature cystic teratomas), neck dermoid cysts, and gastric duplication cysts—but not gastric dermoid cysts 1, 2. If you are evaluating a young adult with a gastric subepithelial mass, you are most likely dealing with a gastric duplication cyst (a congenital foregut anomaly) rather than a dermoid cyst 1.

Clinical Presentation of Gastric Duplication Cysts

Typical Presentation

• Most commonly asymptomatic and discovered incidentally during endoscopy or imaging for unrelated complaints 1
• When symptomatic, patients present with:
  • Intermittent abdominal pain 3
  • Nausea 3
  • Weight loss 3
  • Mass effect symptoms if the cyst enlarges 1
  • Rarely: rupture or bleeding 1

Age and Demographics

• Primarily diagnosed in the pediatric population, but can present in adults as incidental findings 1
• No specific gender predominance for gastric duplication cysts 1

Diagnostic Approach

Endoscopic Ultrasound (EUS) - The Gold Standard

EUS is the definitive diagnostic modality for gastric subepithelial masses and can easily diagnose a duplication cyst 1:

• Shows an anechoic, smooth, spherical or tubular structure with a well-defined wall 1
• Located within or adjacent to the gastric wall 1
• Does not communicate with the gastric lumen 1

EUS-Guided Fine Needle Aspiration (EUS-FNA)

• Perform EUS-FNA to sample cyst fluid contents if the cystic structure is adjacent to the pancreas to rule out pancreatic pseudocyst or pancreatic cystic neoplasm 1
• This distinguishes duplication cysts from other cystic lesions 1

Imaging Characteristics

• MRI is preferred for detailed characterization and surgical planning, showing characteristic features of cyst contents 4, 2
• Ultrasound may show hyperechoic components with acoustic shadowing if complex contents are present 4, 2, 5
• CT scan can identify the cystic nature and relationship to surrounding structures 2

Differential Diagnosis to Exclude

When evaluating a gastric subepithelial mass in a young adult, consider:

• Gastrointestinal stromal tumor (GIST) - most common intramural subepithelial mass, hypoechoic on EUS, requires biopsy for CD117 staining 1
• Pancreatic rest - hypoechoic third-layer lesion with heterogeneous echotexture, often with surface umbilication 1
• Gastric varices - in patients with portal hypertension, shows flow on Doppler 1
• Inflammatory fibroid polyp - hypoechoic in deep mucosa/submucosa without muscularis propria involvement 1

Treatment Algorithm

For Lesions <2 cm

Initial approach: EUS assessment with active surveillance 1:

• If biopsy is feasible and confirms a benign duplication cyst, resection should be performed unless major morbidity is expected 1
• If biopsy is not feasible or yields inadequate material, active surveillance is recommended 1
• Reserve surgical excision for patients whose lesion increases in size or becomes symptomatic 1

For Lesions ≥2 cm or Symptomatic Lesions

Complete surgical excision is the definitive treatment 1, 4, 2:

• Laparoscopic or open surgical resection with complete excision to prevent recurrence 4, 2
• Endoscopic resection may be considered if complete excision without tumor rupture is technically feasible, to minimize morbidity 1
• Surgical approach should be planned based on location and extent of the cyst 4

Specific Surgical Considerations

• For gastric duplication cysts causing persistent symptoms (as in the reported case of a 59-year-old woman), partial gastric resection may be required 3
• Surgery is indicated for: continuously increasing abdominal complaints, mass effect, or risk of complications 3

Follow-Up and Prognosis

For Conservatively Managed Lesions

• Continue evaluation until a definitive diagnosis is obtained—do not assume the mass is benign 4
• Document a plan for follow-up to assess resolution or progression 4
• Advise patients of criteria that would trigger need for additional evaluation 4

Post-Surgical Prognosis

• Excellent prognosis after complete surgical excision of benign gastric duplication cysts 3
• Full recovery expected with appropriate surgical management 3

Critical Pitfalls to Avoid

Do Not Biopsy Without EUS Guidance

• Never perform blind endoscopic biopsy of a subepithelial mass that could be a varix—this risks catastrophic hemorrhage 1
• Always perform EUS first to characterize the lesion 1

Do Not Assume Benignity

• While gastric duplication cysts are benign, malignant transformation can occur in dermoid cysts (though this applies to ovarian dermoids, not gastric lesions) 1, 2, 6, 7
• Squamous cell carcinoma is the most common malignant transformation in dermoid cysts, typically in postmenopausal women 1, 2

Do Not Delay Diagnosis

• For masses with concerning features (present ≥2 weeks, fixed, firm, >1.5 cm), pursue definitive diagnosis aggressively 4
• If diagnosis remains uncertain after EUS, perform FNA rather than open biopsy 4