Mature Teratoma with Malignant Brenner Tumour: A Rare Ovarian Collision Tumour Case Report and Literature Review

Abstract

Collision tumor is existence of distinct tumors in the same tissue or organ without admixture. Although any histological type of ovarian tumor may occur in collision tumor, the mature teratoma is one of the most found component. Brenner tumor is a rare epithelial tumor of ovary and the coexistence of it with teratoma in collision tumour is sparsely reported in literature. Here we describe a case of mature teratoma with malignant Brenner tumor diagnosed post-operatively on histopathological and immunohistochemical examination. It is of paramount importance to correctly diagnose the histological components of collision tumor as it decides further management and course of the disease.

Introduction

Collision tumour is coexistence of two histologically distinct tumours in the same tissue or organ without any admixture at the interface. In the literature, there are reports of collision tumour in organs such as lung, gastrointestinal tract, central nervous system, skin, and uterus but rarely in ovary. Any histological type of ovarian tumour can occur in collision tumour of ovary but so far mature teratomas are the most found component. Brenner tumour is a rare type of epithelial ovarian tumour accounting for 1–2% of all ovarian tumours. These tumours can be benign, borderline, or malignant. The malignant variety is rare and comprises less than 5% of all Brenner tumours. Here, we describe a very rare collision tumour comprising of mature teratoma and malignant Brenner tumour.

Case

A 41-year-old, P3L3 female came to our outpatient department with chief complaints of abdominal pain and distension for 6 months. Clinical examination of abdomen revealed a mobile, non-tender abdominopelvic lump of 20*15 cm size and variegate consistency. There were no ascites. On pelvic examination, same lump was felt through all the fornices, and uterus could not be felt separately from the mass. Following investigations, all her tumour markers were within normal range except CA-125 which was raised to the value of 118.6 U/L. On CECT, there was a huge 14.3*18.9*22 cm thin walled minimally peripherally enhancing hypodense cystic lesion with fat component within it. A large (7.9*4.6 cm) enhancing solid component also noted on the left side of uterus suggestive of the left ovarian mass (Fig. 1A and B). Uterus was bulky and right ovary appeared normal. There were no ascites or lymphadenopathy, and rest of the CT findings were normal. The patient was duly taken up for staging laparotomy following adequate preoperative workup. Intraoperatively, mild ascites and a solid-cystic mass of around 20*15 cm size, arising from the left ovary and infiltrating the descending colon, were noticed. The right ovary and uterus along with bilateral fallopian tubes were unremarkable. Rest of the other abdominal organs appeared smooth and grossly normal. Total abdominal hysterectomy, bilateral salpingo-oophorectomy, total omentectomy, bilateral pelvic, and para-aortic lymphadenectomy along with resection and anastomosis of the part of descending colon infiltrated by tumour were performed to achieve R0 resection. Gross examination of the tumour showed smooth and bosselated external surface, and on cut section, there were the presence of tuft of hair, cartilaginous areas, and a firm nodular area of 6*7 cm along with yellow areas. The specimen of descending colon showed a grey–white firm tumour 3.5*2*0.5 cm which was 4 cm and 7 cm away from distal and proximal resected margin, respectively. The microscopic examination of the left ovarian tumour showed areas of mature cartilage, bony tissue, and areas of squamous epithelium. In addition, there were areas showing nests, lobules, and trabeculae of round to oval cells with stippled chromatin and hyperchromatic nuclei and conspicuous nucleoli with moderate amount of eosinophilic cytoplasm. Mitosis was seen (Fig. 2). There was capsular breach, and the left fallopian tube showed microinvasion by tumour cells. The part of the descending colon showed similar tumour deposits up to submucosa but both resected margins were free of tumour on microscopy. Based on the histopathological examination findings, two differential diagnoses, teratoma with areas of malignant carcinoid tumour and teratoma with malignant Brenner tumour, were made. The final diagnosis of teratoma with malignant Brenner tumour was further confirmed by immunohistochemistry (IHC) which showed GATA3, CK7, and CK20 positivity. Postoperatively, patient received six cycles of adjuvant chemotherapy with carboplatin and paclitaxel. The patient is on regular follow-up and is observed disease free for 2 years.

Fig. 1.

CECT image of the tumour suggesting a large 14.3*18.9*22 cm thin walled minimally peripheral enhancing cystic lesion with fat component and tiny areas of calcification arising from the left ovary. Another 7.9*4.6 cm enhancing solid lesion in the left lower part of the pelvis attached to the uterus, most probably left ovarian mass

Fig. 2.

The microscopic image (H&E section) shows areas of mature cartilage, bony tissue, and squamous epithelium. In addition, there are areas showing nests, lobules, and trabeculae of round to oval cells having hyperchromatic nuclei, conspicuous nucleoli, moderate amount of cytoplasm, and mitosis. Tumour cells (A;40X), mature squamous cells (B;10X), and bone and cartilage (C;10X) with areas of necrosis (D;10X) are marked by black arrow and Walthard cell nests (D) by green arrow

Discussion

Collision tumours are less commonly found in ovaries. The most frequent combination found in published literature is of mature teratoma and cystadenoma, whereas in this case, it was a rarer histological combination of teratoma with malignant Brenner tumour. PubMed search reveals less than 10 such cases documenting collision tumour in ovary composed of Brenner tumour and teratoma.

Collision tumours can occur at any age, in both premenopausal and postmenopausal females but malignant histology is a more common finding in postmenopausal women [1]. Patient generally presents with abdominal pain, distension, lump, or pressure symptoms. The diagnosis is established by histopathological examination but sometimes IHC may be required for confirmation. Any histological variant can coexist in collision tumour but teratoma is the most common component found in such tumours [2].

The exact pathogenesis of collision tumour is unclear, though several hypotheses exist to explain the same. Common origin from pluripotent precursor stem cell that differentiates into two components, simultaneous proliferation of two different cell lines, interaction of carcinogenic agent with different tissues inducing different tumours, and growth of second line tumour promoted by micro-environmental changes such as oncogenic growth factor production induced by primary lesion are few among the hypotheses.

Teratomas are one of the most common benign ovarian neoplasm in females of reproductive age group and account for 10–20% of all ovarian tumours. However, in 1–2% of cases, it may undergo a malignant transformation. Microscopically teratomas contain elements derived from the three germ cell layers; ectoderm (epithelium and neural tissue), endoderm (gastrointestinal epithelium and thyroid tissue), and mesoderm (bone, cartilage, muscle, and fat). These tumours are mostly unilateral and may vary from small cysts to huge masses. However, 80% of the teratomas are reported to be of 10 cm or lesser in size. Radiological evaluation such as ultrasonography and contrast-enhanced computed tomography (CECT) helps in its diagnosis; however, histopathology remains the gold standard.

Brenner tumours are rare benign epithelial tumours affecting postmenopausal females and are identified incidentally on histopathology [3]. The tumour may turn malignant on a rare occasion and may present as solid or cystic mass with mural nodule. Radiologically, Brenner tumour shows nonspecific features and resembles to solid ovarian masses such as leiomyoma, fibroma, or fibrothecoma. On microscopic examination, the tumour is consisted of solid and cystic nests of epithelial cells resembling transitional epithelium surrounded by abundant fibrous stromal components. Most of the studies have shown origin of the Brenner tumour from celomic epithelium; however, its teratomatous origin has not been considered yet in the literature due to very rare occurrence of this histological combination as reported in the present case.

The behaviour of collision tumour depends upon the characteristics of the histological components present in it. The primary treatment modality is optimal surgical resection. There are very few studies on the role of adjuvant chemotherapy for the treatment of malignant Brenner tumour, and the effects of platinum-based chemotherapy and paclitaxel have demonstrated progression-free survival. A case series and review of treatment strategies of 10 cases of malignant Brenner tumour by Zhang Y et al. showed that seven patients who received adjuvant chemotherapy had median progression-free survival (PFS) of 37 months (range: 5–116 months). No patients received adjuvant radiation therapy. Thus, they concluded that these tumours respond well to adjuvant platinum–taxane treatment after complete surgical resection [4].

Conclusion

Collision tumours are rare of its kind, mature teratoma with malignant Brenner tumour, and the prognosis depends upon the histological components herein. Thus, it is of paramount importance to correctly diagnose the histological variant of the tumour for adequate management and favourable prognosis.

Funding

Nil.

Declarations

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical approval

Taken from institute ethics committee.

Informed consent

Not obtained in the present case, as there is no disclosure of patient’s identity.