Teratoid Cyst with Nephrogenic Elements: A Rare Case

Teratoid cyst is a type of dermoid cyst, the lining of which varies from stratified squamous to a ciliated respiratory epithelium containing derivatives of ectoderm, mesoderm and endoderm. The most common location of this cyst is oral cavity and presence of nephrogenic elements has been very rarely reported. We report a very uncommon rare case of teratoid cyst with nephrogenic elements in cyst wall and intestinal duplication cyst in a 6-month-old-female child.


Introduction
In 1955, Meyer updated the concept of dermoid cyst to describe three histological variants, that is, the true dermoid, epidermoids and teratoid cyst. True dermoid cysts are cavities lined with epithelium with keratinization and skin appendages in cyst wall. Epidermoid cysts do not show skin appendages. The lining of teratoid cyst varies from stratified squamous to a ciliated respiratory epithelium containing derivatives of ectoderm, mesoderm and endoderm. [1] Teratoid cyst is the least common of the three variants of dermoid cysts. [2] Search by Ranabhat et al revealed oral cavity to be the most common location of this cyst. Other locations where these cysts have been reported in are mandible, submental region, large intestine, mediastinum, thymus, nasopharynx, spinal cord, kidney, and the eyes. [3] We report an unusual case of intestinal duplication cyst and teratoid cyst in a single patient with rare nephrogenic elements in the teratoid cyst wall, to the best of our knowledge such case with teratoid cyst with nephrogenic elements and intestinal duplication cyst together has never been reported before.
Only single case of teratoid cyst containing nephrogenic elements has been reported so far. [4] Case Report 6-month-old female child presented with vomiting of two days duration. Ultrasonography of abdomen and pelvis revealed well defined double wall cystic lesion measuring 10.2 x 4.8 x 4.4 cms extending from right hypochondriac region to inferiorly umbilical and hypogastric region. Possibilities included were bowel duplication cyst/ intraperitoneal cyst. Another scan revealed focal dilatation of colonic segment in left paraumbilical region. Both the kidneys appeared normal on sonography. Intraoperatively ascending colon duplication cyst was excised. Another left sided cyst, noted close to sigmoid colon, was also excised.
We received two specimens, larger one comprising ileocaecal junction, appendix and ascending colon. On microscopy [ Figure 2] duplication cyst was lined by squamous, gastric, colonic and respiratory type of columnar mucosal epithelium and had separate muscle coat from the intestinal wall. The final impression of this larger specimen was Intestinal duplication cyst.
The second smaller sample, revealed a cyst lined by squamous, gastric, colonic and respiratory type of columnar mucosal epithelium. Wall showed smooth muscle bundles and nodules of primitive and developing nephrogenic elements with formation of tubules and glomeruli. The final impression of this specimen was teratoid cyst with primitive and developing nephrogenic elements [ Figure 3].
www.pacificejournals.com/apalm eISSN: 2349-6983; pISSN: 2394-6466 cysts. Out of these six, teratoid cyst has been observed to be very rare. [3] Dermoid cysts are regarded as either congenital in origin, when they are sometimes known as benign teratomas, or acquired due, it is supposed, to traumatic implantation of epidermal tissue and then are sometimes referred to as epidermoid cysts. Congenital dermoids, or benign teratomas, which strictly are neoplasms with elements of all three germinal layers, arise commonly in the ovary, less so in the testis, and in midline sites. Here they theoretically arise as a result of failure of embryological fusion. The exact origin of teratomas of the gonads remains unclear, however, dermoid cysts have in fact been described in many other locations: in the kidney, liver, colon, stomach, mesentery and lung. [5] Teratoid cyst are lined by epithelium ranging from keratinizing squamous to pseudostratified columnar respiratory epithelium with dermal appendages in the connective tissue wall along with derivatives of all three germ layers (ectoderm, mesoderm and endoderm). [1] The differential diagnoses in our case were: benign cystic teratoma, extrarenal Wilm's tumour, or a teratoid cyst containing nephrogenic tissue. Due to absence of immature blastemal elements, extrarenal Wilm's tumour was ruled out. Mature cystic retroperitoneal teratoma with C-162

Teratoid Cyst with Nephrogenic Elements
Annals of Pathology and Laboratory Medicine, Vol. 7, Issue 9, September, 2020 well differentiated renal elements is reported by Sinha et al [6] and a teratoid cyst containing nephrogenic tissue in a woman with a horseshoe kidney [4]  contiguity to any segment of the alimentary tract . [7] All these criterias were fulfilled in our case.
In patients with symptomatic colonic cysts, surgical resection is usually recommended in good operative candidates. [8] Teratoid cyst was also excised in all the literatures studied. [1,2,3,4] Combination of these two entities has never been reported before, to the best of our knowledge.

Conclusion
Paediatric patients can present with multiple abdominal lesions. Teratoid cyst and intestinal duplication cyst are rarer such lesions. Hence reporting this case, with simultaneous occurrence of both the lesions in a single patient and presence of very uncommon nephrogenic elements in the teratoid cyst wall with its uncommon location of occurrence.