Adult Ovarian Retinoblastoma Genomic Profile Distinct From Prior Childhood Eye Tumor

We report the first case of a woman, previously cured of childhood intraocular retinoblastoma, who developed tumor in the ovary with histological and genomic characteristics suggesting an independent retinoblastoma, not a metastasis.

In a 10-month-old girl with esotropia for 6 months, the right eye was classified as group IVb (Reese-Ellsworth classification)/group D (International Intraocular Retinoblastoma Classification) and the left eye was classified as group Vb/group D.¹ There was no extraocular disease on computed tomography or bone marrow and cerebrospinal fluid examinations. She was cured by irradiation of the right eye and enucleation of the left eye. There was no tumor extension into the choroid or optic nerve.

At age 19 years, she had constipation and abdominal distention, with a large abdominal mass on computed tomography (Figure 1A and B). After an open biopsy, she underwent laparotomy for resection of a left ovarian tumor and fallopian tube, mesentery, and lymph nodes, which were involved by tumor, and drainage of 5 L of ascites containing no tumor cells. The variegated, white-tan-pink, bosselated, 24 × 19 × 15-cm ovarian tumor contained solid, cystic, and gelatinous areas separated by fibrous septae. Small, round, blue cells with molded round-to-ovoid nuclei and scant eosinophilic cytoplasm were arranged in nests and lobules (Figure 1C), amidst uninvolved ovarian stroma and follicles (Figure 1D) that were positive for vimentin (Figure 1E) and ovarian markers. There was no teratoma. Mitotic figures and apoptotic bodies were common (Figure 1F). The concurrent presence of Homer Wright (Figure 1G) and Flexner-Wintersteiner (Figure 1H) rosettes was pathognomonic for retinoblastoma. Tumor cells stained positively for CD56, MIB-1, and synaptophysin (Figure 1I-K) but did not colocalize with ovarian markers.

Postoperatively, her tumor recurred rapidly, but she responded to 4-cycle carboplatin-etoposide chemotherapy. She received etoposide-melphalan conditioning and autologous stem cell rescue of bone marrow, but she relapsed and died 9 months later.

The patient was heterozygous in blood and homozygous in the eye and ovarian tumors for a C to G point mutation causing an immediate nonsense codon in exon 23 of the RB1 gene (TAC → TAG, Tyr790X).

The DNA from the ovarian and eye tumors was tested by quantitative multiplex polymerase chain reaction² for copy number changes in the KIF14, DEK, E2F3, and MYCN oncogenes and the CDH11 tumor suppressor gene, which constitute post-RB1 mutations in retinoblastomatumorigenesis.^2,3ACVRL1 and RLBP1 were used as 2-copy controls (Figure 2), normal blood was used as a negative control, and a retinoblastoma with known KIF14, DEK, E2F3, and MYCN gains and CDH11 loss was used as a positive control. Distinct profiles were observed: the eye tumor showed gain of KIF14 (mean copy number, 2.77) and MYCN (mean copy number, 4.80) with single-copy CDH11 (mean copy number, 1.04), whereas the ovarian tumor showed no KIF14 gain, amplification of MYCN (mean copy number, 19.50), and 2-copy CDH11 (mean copy number, 2.21) (Figure 2). DEK and E2F3 were not gained in either tumor.

We consider 2 possible explanations for our observation of retinoblastoma manifesting in the ovary: late metastasis or independent malignant transformation. Late metastasis is unlikely 18 years after cured retinoblastoma. Metastasis usually occurs in the first few years after diagnosis. Ovaries are extremely rare sites, reported in only 1 other case after 2 years.⁴ Malignant transformation of retinal cells within an ovarian teratoma 15 years after cured retinoblastoma has been reported, but without the molecular characterization we show.⁵

Our patient had no teratoma. She developed an ovarian tumor with histological (Figure 1) and molecular (Figure 2) features of retinoblastoma. Ovarian markers were observed only in uninvolved ovarian tissue, while the proliferative tumor stained for retinoblastoma markers and displayed Homer Wright and Flexner-Wintersteiner rosettes, pathognomonic for retinoblastoma. The eye and ovarian tumors both shared the same first (M1) and second (M2) RB1 mutations, likely from loss of the normal RB1 allele and reduplication of the mutated allele (loss of heterozygosity), which is observed in 52% of retinoblastoma cases.⁶

The different pattern of post-RB1 mutational events in the ovarian tumor suggests a separate clonal origin from the eye tumor. Common for retinoblastoma, the eye tumor displayed gains of KIF14 and MYCN with loss of 1 copy of CDH11.³ The ovarian tumor showed only MYCN amplification with a normal CDH11 copy number (Figure 2). MYCN amplification may account for the aggressiveness of the ovarian tumor, as it does for highly fatal neuroblastomas.⁷

The evidence indicates that the ovarian tumor was an independent retinoblastoma rather than a metastasis. While our analysis did not attempt to reveal the cell of origin that underwent malignant transformation, marker analysis revealed that it was not of ovarian origin. Instead, we speculate that it may have been a retinal cell displaced into the ovary by an unknown mechanism. Alternatively, a primitive pluripotent cell persisting in the ovary may have acquired the second RB1 and subsequent other mutations allowing the malignant transformation.

Correspondence: Dr Chan, Division of Hematology/Oncology, The Hospital for Sick Children, 555 University Ave, Toronto, ON M5G 1X8, Canada (hslchan@attglobal.net).

Funding/Support: This work was supported in part by a grant from the Ontario Institute for Cancer Research and The Terry Fox Research Institute (Drs Gallie and Chan), by the Canadian Retinoblastoma Society, by the Royal Arch Masons of Canada (Dr Gallie), and in part by the Ontario Ministry of Health and Long-Term Care.

Disclaimer: The views expressed do not necessarily reflect those of the Ontario Ministry of Health and Long-Term Care.