Case report of bilateral ovarian fibromas associated with de novo germline variants in PTCH1 and SMARCA4.

Background: Ovarian sex cord-stromal tumors (OSCTs) are rare ovarian tumors that can develop from sex cord, stromal cells, or both. OSCTs can be benign or malignant. Bilateral and/or unilateral ovarian fibromas, a type of OSCT of the stromal cells, have been reported in individuals diagnosed with nevoid basal cell carcinoma syndrome (NBCCS). Calcified ovarian fibromas have been reported in 15-25% of individuals diagnosed with NBCCS while 75% of those cases occur bilaterally. The average age at diagnosis of OSCT/ovarian fibromas in patients with NBCSS is in the second to third decade compared with age 50 in the general population. Ovarian tumors are rare in pediatric populations.

Methods: The patient is a 5-year-old female diagnosed with bilateral ovarian fibromas at age 4. Multigene panel for the patient and subsequent targeted molecular evaluation of parents were completed. Histological evaluations on the surgically resected ovaries were performed for microscopic characterization of fibromas.

Results: Germline testing identified de novo heterozygous novel likely pathogenic variants in PTCH1 gene, exon 12 deletion, and an SMARCA4 splicing variant c.2002-1G > A. Microscopic examination of bilateral tumors was consistent with an ovarian fibroma.

Conclusions: To our knowledge, this is the first report of bilateral benign ovarian fibroma in a child with a diagnosis of nevoid basal cell carcinoma syndrome (NBCCS) with a potential predisposition to Rhabdoid Tumor Predisposition Syndrome (RTPS).