Mature teratomas are benign germ cell tumors that predominantly occur in gonadal regions. Extra-gonadal teratomas, especially in the umbilical region, are rare and often present significant diagnostic challenges. A delayed presentation with umbilical perforation in absence of congenital abdominal wall defects is uncommon. A 9-year-old female presented with a four-year history of progressively enlarging umbilical mass with occasional discomfort. Examination revealed a firm, pedunculated mass protruding through a perforated umbilicus. A contrasted CT scan, revealed a well-encapsulated heterogeneous mass containing calcifications, with no evidence of deep intra-abdominal involvement. Complete surgical excision of the tumor was performed. Histopathological analysis confirmed a mature teratoma. Recovery was uneventful, and follow-up showed no recurrence. Umbilical teratomas are rare entities, particularly in children without congenital abnormalities. This case illustrates delayed presentation of umbilical perforation and diagnostic challenges in unusual located teratoma, emphasizing the need for high suspicious index when evaluating persistent umbilical masses. Radiology plays a critical role in differentiating these tumors from other conditions like granulomas, infections, or congenital anomalies. Complete surgical excision is the treatment of choice. This report highlights the rarity and diagnostic complexity of mature teratomas in atypical locations. Early recognition of this rare differential diagnosis in cases of persistent umbilical symptoms is essential to prevent complications such as infection and perforation. Awareness and early intervention are critical to achieving favorable outcomes in such cases. This case contributes to the limited literature on extragonadal teratomas with umbilical perforation and the need for timely diagnosis and management.

Mature extragonadal teratomas, particularly at the pelvic extraperitoneal site, are rare. Herein, we report a case of paravaginal teratoma and fistula formation five years post-operation. A 23-year-old woman (G4P3A1) presented with a left paravaginal cystic tumor. After transvaginal tumor excision, histopathology revealed a paravaginal dermoid cyst. Five years post-operation, she returned with recurrent symptoms, including fever and perineal pain. Pelvic magnetic resonance imaging showed abscess at the surgical site, with tract-like extensions through the levator ani and vaginal wall. Treatment was administered without surgical intervention. Seven years post-operation, the patient underwent debridement of the left paravaginal abscess via the left perineal route. The patient was diagnosed with an abscess and an epidermal keratinous cyst with a vaginoperineal fistula. No recurrent abscess or fistula formation was encountered four years after debridement and fistulectomy. Preoperative and postoperative counseling should be conducted with long-term follow-up for such patients.

Mature teratomas of the duodenum are extremely rare, with only five cases reported in the English literature and none documented in Vietnam. Malignant transformation within a mature teratoma presents a challenging scenario for diagnosis and management, requiring a nuanced approach to treatment. We report the first documented case of malignant transformation in a duodenal mature teratoma in Vietnam. A 35-year-old male presented with persistent dull pain in the left flank, anorexia, and melena. Clinical examination revealed a palpable 10 × 14 cm mass in the left hypochondrium. Computed tomography (CT) imaging identified a tumor in the D4 segment of the duodenum with invasion into adjacent structures. The patient subsequently underwent surgical resection of the tumor, followed by adjuvant chemotherapy. Histopathological analysis of the resected mass confirmed a moderately differentiated squamous cell carcinoma arising from a mature teratoma. Malignant transformations within teratomas, especially in such rare locations as the duodenum, require a multidisciplinary approach for optimal patient outcomes. In this case, the combination of surgical and adjuvant therapies was critical to managing the disease. This case highlights the importance of early recognition and a multidisciplinary approach in managing malignant transformation in duodenal teratomas. The combination of surgery and adjuvant chemotherapy proved effective, with no recurrence or metastasis observed at five months follow-up.

Mediastinal teratoma is a rare extragonadal teratoma that frequently manifests with non-specific symptoms and is commonly misdiagnosed, particularly in Indonesia, where tuberculosis (TB) is endemic. Herein, we present two cases of children aged 19 months and 17 years old who were referred with chronic nonspecific symptoms of cough, tachypnea, chest pain, and hemoptysis. Both children were initially diagnosed with TB and both completed anti-tuberculosis treatment. After visiting several healthcare facilities, a mediastinal mass was finally diagnosed and they all underwent thoracotomy without any further complication. The histopathology findings revealed mature teratoma. All patients had satisfactory outcomes at follow-up visits. Patients presented with non-specific symptoms are often clinically diagnosed with TB. However, primary healthcare doctors should consider other differential diagnoses when a child has non-specific respiratory symptoms, especially when chest X-ray findings are nonspecific and TB workup is negative. The diagnosis of mediastinal masses is still challenging in Indonesia, as the diagnosis requires a vast array of work-up examinations, therefore, early recognition and referral are crucial for management.

Extragonadal parasitic dermoid cysts are rare. Diagnosis of such extragonadal parasitic teratoma is often done intraoperatively during surgical exploration of abdominal mass.