Gluteal teratoma: A rare site of extragonadal teratoma.

Extragonadal teratomas are rarely encountered in infants and children. These tumors are reported in retroperitoneum, floor of the mouth, mediastinum, craniofacial region or even in the solid organs of the body. Most of the gluteal teratomas reported in the literature are in fact, lateralized sacrococcygeal teratomas. We are reporting a case of unilateral big gluteal teratoma in a 6-year-old girl. The tumor did not have any connection with the sacrum or coccyx and was successfully removed. Histology showed well-differentiated bowel as well as fetiform structures.

INTRODUCTION

Extragonadal teratomas are rare tumors and usually present during infancy or early childhood. These tumors may arise in unusual locations and have characteristic fetiform pattern. Although surgical excision is curative, their location near important organs may make complete excision very challenging. This report entails successful surgical excision of a large teratoma in the gluteal region, which clinically appeared to be a lipoma in a young girl.

CASE REPORT

PG, a 6-year-old girl presented with a swelling in her left buttock, which was present since birth. The swelling was gradually increasing in size, and she had pain and discomfort while seating. The tumor was bulky and soft on palpation and could be separately felt from the sacrum and coccyx. A contrast computed tomography and magnetic resonance imaging (MRI) scans showed well-encapsulated contrast-enhanced bowel loops with other soft tissue elements [Figure 1]. Serum alpha-fetoprotein level was normal. On exploration, well-developed colon and small bowel loops were seen along with small cysts, bones, and muscle elements [Figure 2]. The tumor was completely excised along with its sac; redundant skin and subcutaneous tissues were excised. The patient recovered well and was discharged on day 6. The histology showed the structure of normal colon and small bowel with areas of fetiform structure in soft tissues. Derivatives of endoderm, mesoderm, and ectoderm were identified. Fetiform structure also contained mature respiratory epithelium with rudimentary cartilage and gut mucosa. The patient has been on follow-up for 16 months. At last follow-up, the scar was healthy and there was no evidence of recurrence.

Figure 1

Magnetic resonance imaging scan showing encapsulated mass with bowel loops and soft tissues

Figure 2

The mass with well-developed colon segment

DISCUSSION

Extragonadal teratomas of childhood are rare tumors and may occur in unusual locations such as, retroperitoneum, mediastinum, craniofacial region or even in the solid organs (liver, kidney). These tumors often present with acute symptoms and may have some distinctive features such as an unusual location and a “fetiform” histotype of the lesion. Some tumors are detected on antenatal ultrasound and treatment in such cases can be initiated early to prevent complications. Tumors occurring in unusual sites may cause problem because of their anatomical location and size. An emergency surgery may sometimes be needed because of mass effect of the tumor.

Bhalla et al. reported 267 cases of teratomas, of which 10 cases occurred at rare sites, such as retroperitoneal space (3 cases), floor of the mouth (3) and one each in the kidney, mediastinum, thyroid gland, and the urinary bladder.[1] Two of these tumors were solid. All these 10 tumors had foci of immature elements.

Paradies et al. reported 4 cases of teratomas at unusual sites in 2 neonates, 1 infant, and one 4-year-old child.[2] Two neonates had tumors detected on antenatal ultrasonography and 3 patients presented with acute symptoms requiring emergency surgery. Two neonates had tumors in temporozygomatic region and abdomen, respectively. The infant had a tumor arising from the liver and the older child had a retroperitoneal tumor. All these tumors had mature elements on histology.

Lange described a benign cystic teratoma in the gluteal region.[3] Perez Carro et al. used MRI to differentiate a gluteal teratoma from more common tumors in this site arising from fat or fibrous tissue.[4]

Fetiform teratoma is a distinct entity with highly organized differentiation but without visceral organ differentiation. However, Kuno et al. described a fetiform teratoma with both a highly developed axial skeleton and organs that included a brain, eyelike structure, trachea, thyroid gland, blood vessels, gut, and phallus like structure. Remarkably, skeletal muscle has never been documented in a teratoma.[5] In the present case, well-developed colon and small bowel loops were noted inside the teratoma. However, the tumor had no connection with the sacrum or coccyx. Most of the gluteal teratomas reported in the literature are, in fact, sacrococcygeal teratomas presenting in a lateral location. Sood et al. reported an 11-year-old girl who presented with a fetiform gluteal mass attached to the sacrum by a fibrous band.[6] Gajbhiye et al. also reported a 4-month-old girl with anorectal malformation, who had a gluteal mass.[7] The mass was excised and found to be a sacrococcygeal teratoma. Jan et al. described a case of lateralized cystic sacrococcygeal teratoma mimicking gluteal abscess.[8]

Children with extragonadal tumors may present with complications necessitating urgent surgery. In elective cases, it is ideal to have estimation of serum alpha-fetoprotein level and proper imaging studies to know about the characteristics and extent of the tumor. Serial section of the excised mass is important, especially in older children to detect any immature neuroepithelial elements or elements of yolk sac tumor.