Purpose or Case Report: To determine the spectrum of abnormalities associated with DICER1 syndrome.
To review imaging studies performed in oncologic staging and surveillance.
To delineate the screening protocol used in those with positive genetic testing.
Methods & Materials: This research ethics board approved retrospective study evaluated genetically confirmed or suspected DICER1 pediatric patients referred to our tertiary institution between 2004-2015.
Patients with tumors such as pleuropulmonary blastoma (PPB) or pineoblastoma (PNB) in isolation with no other features of DICER1 spectrum were excluded.
Modality type and timing was captured and imaging analyzed to determine what related to staging; to treatment e.g. screening for infection, line insertions; and to cancer predisposition screening.
Results: There were 12 patients (5 male and 7 female) with mean age at presentation of 4.6 years (range 14 days to 8 years). We included all patients with a confirmed genetic diagnosis (10) and strong clinical history (2) whose parents did not consent to genetic testing.
During the study period, our patients underwent 619 imaging studies (139 x-rays, 186 ultrasounds, 99 CTs and 195 MRIs). This included oncologic staging and follow-up, and surveillance imaging, some elements suspended during active cancer treatment.
The screening protocol for additional tumors in those with known malignancies, and at risk for neoplasia but with no known tumors, started as early as 14 days old, the youngest age at first malignancy being 1 year.
Screening initially consisted of a chest x-ray, abdominal and neck ultrasound and dedicated brain MRI. Novel technique whole body MRI was introduced during the study period, performed simultaneous to the brain MRI, substituting the chest x-ray, to minimize ionizing radiation.
DICER1 related pathology included malignant lesions in 75% of patients: 4 PPB, 2 PNB, 2 ovarian sex cord stromal tumors and 1 renal sarcoma. No patient had > 1 malignancy during the study period.
Benign lesions in 83% of patients included: 2 cystic nephromas, 3 thyroid nodules, 3 thyroid cysts, 1 renal cyst and 1 pineal cyst.
Two subjects, confirmed with DICER1, who were relatives of index cases, had no tumors.
Conclusions: Given the high incidence of neoplasia in DICER1 and early age at first presentation, early screening of at risk patients is critical, as is awareness of the types of DICER1-related tumors.
The current DICER1 screening protocol used in our institution includes an abdominal and neck ultrasound, and whole body and brain MRI.