Adrenal and Mesenteric Teratomas in Infants: Common Tumors in Uncommon Sites.

Teratomas are common tumors in children. The most common sites are gonads, however, several extragonadal sites are well known such as sacrococcygeal region, mediastinum, head and neck, stomach, and vagina. Occasionally, teratomas occur in unusual sites which pose diagnostic difficulties. Here, we describe two cases of infantile teratomas with unusual presentation. The first case was a 6-month-old girl who presented with a mass in the right side of the abdomen. Computed tomography (CT) scan showed a solid-cystic mass in the right suprarenal region. The second was a 4-month-old boy who came with a huge abdominal mass. Contrast-enhanced CT showed a tumor arising from the jejunal mesentery. On microscopic examination, they were diagnosed as mature and immature teratoma, respectively. Although neuroblastoma is the most common infantile adrenal neoplasm, the possibility of teratoma should be considered for cystic adrenal lesions. Mesenteric teratoma can be difficult to distinguish radiologically from the more common lymphangioma; however, accurate diagnosis is important in view of long-term follow-up for teratomas because of the possibility of malignant transformation. Copyright:

INTRODUCTION

Teratomas are one of the most common neoplasms of the pediatric age group. In children, the most common sites are sacrococcygeal region (65%), mediastinum (11.7%), gonads (10%20%), and retroperitoneal sites (5%). Less than 5% are intracranial, cervical, and gastric.[12] Other rare sites are ileum, tongue, vagina, and nasopharynx.[2] Primary adrenal and mesenteric teratomas are rare in pediatric population, yet it is important to make the correct diagnosis in view of the long-term follow-up. Here, we describe two cases of infantile teratomas arising from the adrenal gland and mesentery, respectively.

CASE REPORTS

Case 1

A 6-month-old girl presented with a mass in the right side of the abdomen. Computed tomography (CT) scan of the abdomen showed a heterogeneous solid-cystic mass in the right suprarenal region with focal evidence of calcification [Figure 1a]. Radiologically, the diagnosis of a cystic neuroblastoma (NB) was suggested. Fine-needle aspiration (FNA) from the mass showed scanty material, and urinary vanillylmandelic acid level was normal. Meta-iodobenzylguanidine (MIBG) scan was performed and was negative. The mass was resected and on gross examination, a bosselated, ovoid mass measuring 5 cm across with tail of adrenal attached to one end was identified. [Figure 1b]. Microscopic examination showed a tumor of variegated appearance and was composed of the skin with dermal appendages, mature neuroepithelium, bone, cartilage, fat, fibrous tissue, and glandular elements. No immature elements were seen. A compressed rim of adrenal cortical tissue was noted at periphery [Figure 1c-f]. On the basis of histology, a diagnosis of mature adrenal teratoma was made. The child is doing well on 1-year follow-up.

Figure 1

(a) Computed tomography scan abdomen showing a heterogeneously enhancing mass in the right suprarenal region with solid-cystic areas. (b) Gross photograph showing variegated appearance and tail of adrenal in lower aspect (arrow); inset showing higher magnification. (c) Low magnification of tumor showing lobules of cartilage and glands (H and E, ×100). (d) Low magnification showing mature neuroepithelium (H and E, ×100). (e) Low magnification showing gut epithelium and squamous epithelium (H and E, ×100). (f) Scan view showing sliver of adrenal at the periphery (H and E, ×40); inset showing high magnification of compressed adrenal (H and E, ×400)

Case 2

A 4-month-old boy presented with a huge abdominal mass. Contrast-enhanced CT abdomen revealed a large heterogeneous solid-cystic mass in the mesentery. A diagnosis of lymphangioma was suggested. During excision, mass was seen to arise from the mesentery and gross examination showed a variegated solid-cystic mass measuring 5 cm across [Figure 2a]. Microscopical examination showed a tumor with variegated elements such as skin with dermal appendages, bone, cartilage, muscle, adipose tissue, and glandular elements. In addition, extensive areas of neuroglia were present. Immature neural elements, rosettes, and immature renal tissues were identified [Figure 2b-f]. Based on these features, a diagnosis of immature teratoma was made. Serum alpha-fetoprotein (AFP) level was slightly raised on the 3rd postoperative day. The child is doing well on 1-year follow-up with normal serum AFP levels.

Figure 2

(a) Computed tomography of the abdomen showing a heterogeneously enhancing mass in the left abdomen and pelvis with solid-cystic component; inset showing gross photograph of the specimen. (b) Low power of tumor showing lobules of cartilage and glands (H and E, ×100). (c) Low power of tumor showing gut epithelium and glandular structures (H and E, ×100). (d) Low power showing immature neuroepithelium (H and E, ×100); inset showing high power of the same (H and E, ×400). (e) Low power of the tumor showing ectopic immature renal tissue (H and E, ×100); inset showing high power of immature glomeruli (H and E, ×400). (f) High power of tumor showing choroid plexus (H and E, ×400)

DISCUSSION

Teratoma is a common germ cell tumor, and gonads are the most common site. Unlike in adults, extragonadal sites are fairly frequent in children.[123]

There are two main hypotheses regarding the development of extragonadal teratomas. Germ cells appear in the yolk sac during the 4th week of intrauterine life and migrate along the dorsal root mesentery to reach the gonadal ridges in around 6th week of intrauterine life. According to Tellium, the extragonadal germ cell tumors arise from the aberrantly migrated primordial germ cells which undergo malignant transformation. This theory only explains the teratomas developing along the midline, however, teratomas are known to occur in nonmidline sites as well. The other hypothesis of Sano states that abnormally migrated pluripotential embryonic cells in different organs may give rise to germ cell tumors.

Extragonadal sites account for 15% of all the teratomas, and the retroperitoneum is the least common location.[123] Retroperitoneal cystic teratomas are associated with bimodal peak in incidence, one in the first 6 months of life and the other in early childhood.

Adrenal teratomas in infants are distinctly uncommon, and only seven cases have been reported in literature till now.[4] Adrenal teratomas, being retroperitoneal, are usually asymptomatic initially. Patients present with abdominal distension, back pain, or intestinal obstruction only when the tumor mass is significantly large. Radioimaging plays an important role in differentiating adrenal lesions. In general, a heterogeneously enhancing mass with solid-cystic areas and occasional calcification are noted, however, these findings are not specific for teratomas. Differential diagnosis includes other common adrenal tumors in infants like NB. In the case of cystic lesions, other differentials such as cystic NB, adrenal cyst, lymphangioma, and adrenal cortical tumor with cystic and myxoid change must be considered.

Accurate preoperative diagnosis is imperative for NB which must be differentiated from the more common Wilms tumor. Aspirate from NB is fairly cellular, but in our case, FNA yielded scanty material. Microscopic diagnosis of teratomas is relatively straightforward, and the presence of mature elements of different germ cell layers clinches the diagnosis. However, to differentiate primary adrenal teratomas from other retroperitoneal teratomas impringing on the adrenal, gross and microscopic evidence of compressed adrenal tissue in the periphery is useful.

Teratomas arising from the mesentery are uncommon.[5] They usually present as an abdominal lump or with features of obstruction. Radiologically, it is difficult to distinguish from other mesenteric lesions such as mesenteric cyst, lymphangioma, and enteric duplication cysts.

Most of the mesenteric teratomas are benign in nature, however, about a quarter may contain immature elements. Immaturity is usually diagnosed by primitive neuroepithelium, however, in rare cases, immature teratomas may also contain immature renal and pulmonary tissues as well. We have previously reported the presence of ectopic immature renal tissues in gastric and sacrococcygeal teratomas.[1] Norris system of grading is widely used to determine the degree of immaturity and prognosis. Immature teratomas are often associated with microscopic features of yolk sac elements, and those teratomas are likely to undergo malignant transformation. Immature glomeruli can sometimes mimic Schiller–Duval body of yolk sac tumor. Extensive sampling of the specimen and follow-up with serum AFP levels is necessary to rule out malignant change.

The prognosis of infantile teratomas is generally favorable unlike adolescents and adults. Even in the presence of immaturity, the outcomes are significantly better, however, a long-term follow-up is suggested.

CONCLUSION

Teratomas at unusual site pose diagnostic difficulties. Cystic and calcified masses of the adrenals in infants are not always NBs. Imaging findings along with careful assessment of histological features are essential for correct diagnosis.

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Conflicts of interest

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