Nevoid basal cell carcinoma syndrome with a unilateral giant ovarian fibroma in a Japanese 6-year-old girl

Nevoid basal cell carcinoma syndrome (NBCCS) is characterized by basal cell carcinoma, skeletal abnormalities, benign tumors including ovarian fibroma, and various other phenotypic expressions. Ovarian fibromas in NBCCS before puberty are very rare. We report a 6-year-old prepubescent girl with NBCCS showing skeletal abnormalities, medulloblastoma, and ovarian fibromas. The patient was referred to our hospital owing to abdominal distension. On admission, a huge elastic hard tumor was palpable and computed tomography showed a huge tumor of the left ovary. We performed a left salpingo-oophorectomy and diagnosed the tumor as a benign fibroma. Further examination of the computed tomography images showed skeletal abnormalities. In addition, the patient had a history of medulloblastoma at the age of 4 years. Therefore, we diagnosed NBCCS. A genetic examination indicated a novel 1 bp deletion in exon 18 (c.3055delG). Sequence analysis of exon 18 using DNA from the ovarian tumor revealed a mutant allele (c.3055delG) dominant to the wild-type allele, thus suggesting loss of heterozygosity in the PTCH1 gene, which is known to be associated with NBCCS. Conclusion On the basis of our experience, physicians treating pediatric ovarian tumors should be aware that such huge benign ovarian tumors may be a phenotype of NBCCS, as shown in our patient. In addition, genetic examination focusing on the PTCH1 gene might be important for diagnosis of NBCCS in pediatric patients.