Project Title

Cystic Nephroma in a Child with DICER1 Mutations

Authors' Affiliations

Bethany Faust, Quillen College of Medicine, East Tennessee State University, Johnson City, TN. Candelaria Deimundo-Roura MD, Department of Pediatrics Quillen College of Medicine, East Tennessee State University, Johnson City, TN. Cara E. Morin MD PhD, St. Jude Children’s Research Hospital, Memphis, TN. Marcela Popescu MD, St. Jude Tri-Cities Affiliate Clinic, Johnson City, TN & Department of Pediatrics Quillen College of Medicine, East Tennessee State University, Johnson City, TN.

Faculty Sponsor’s Department

Pediatrics

Additional Sponsors

Dr. Marcela Popescu

Type

Oral Competitive

Classification of First Author

Medical Student

Project's Category

Tumors

Abstract Text

Cystic nephromas are rare, multiloculated cysts on the kidneys that occur mostly in early childhood. They are considered to be on the same spectrum as cystic partially differentiated nephroblastomas (CPDN) and Wilm’s tumors (WT). They are mostly benign, however, when cystic nephroma is associated with DICER1 mutation, the patient is predisposed to other, more aggressive tumors. DICER1 mutations are not seen in CPDN or WT, so molecular evaluation can help differentiate between them if the histology is unclear. The DICER1 gene is on chromosome 14 and it functions to make microRNA that attaches to mRNA and represses protein synthesis. Mutations of this gene predispose patients to neoplasms on various organs such as the lung, kidneys, ovaries, and thyroid. The data in this case report was gathered via direct patient care and patient chart review. An 18-month-old previously healthy female was hospitalized for a newly diagnosed abdominal mass found on palpation during a well child evaluation. The ultrasound revealed a 9 cm cystic mass on the left kidney and the patient was subsequently sent to St. Jude Children’s Research Hospital. Further evaluation via CT scan has shown a large left renal mass that invaded the ureter and bladder, as well as enlarged lymph nodes in the left suprarenal space and a single 3mm right pulmonary nodule. At this time, cystic Wilm’s tumor was considered and the patient underwent a left radical ureteronephrectomy with lymph node sampling. Cytology report of the pelvic fluid had some inflammatory cells, but no tumor cells were seen in the sample. All of the sampled lymph nodes were also negative for tumor cells. The histological analysis of the mass revealed multiple cystic cavities separated by septa. No blastemal elements (WT1 immunostain was negative) or distinct solid areas were identified, which made the diagnosis of cystic Wilm’s tumor unlikely. The diagnosis of cystic nephroma (CN) vs cystic partially differentiated nephroblastoma (CPDN) is determined histologically by looking at the components of the septa – which, in this case, due to a marked inflammatory infiltrate expending the septa, made the morphology be more congruent with CPDN. Molecular testing of the tumoral tissue identified two DICER1 mutations (DICER1 frameshift mutation and DICER1 D1709E). Patient was subsequently diagnosed with Cystic Nephroma Stage I and further surveillance will be continued to monitor for more neoplasms associated with this mutation. This case highlights a rare disorder that predisposes patients to multiple neoplasms. Histology may not always be sufficient in determining the diagnosis, especially in differentiating CN from CPDN. Molecular evaluation may be helpful for the initial diagnosis and in order to provide adequate genetic counseling. Clinicians should be aware of DICER1 syndrome so they can adequately survey the at-risk patients for a range of benign and malignant neoplasms.

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Cystic Nephroma in a Child with DICER1 Mutations

Cystic nephromas are rare, multiloculated cysts on the kidneys that occur mostly in early childhood. They are considered to be on the same spectrum as cystic partially differentiated nephroblastomas (CPDN) and Wilm’s tumors (WT). They are mostly benign, however, when cystic nephroma is associated with DICER1 mutation, the patient is predisposed to other, more aggressive tumors. DICER1 mutations are not seen in CPDN or WT, so molecular evaluation can help differentiate between them if the histology is unclear. The DICER1 gene is on chromosome 14 and it functions to make microRNA that attaches to mRNA and represses protein synthesis. Mutations of this gene predispose patients to neoplasms on various organs such as the lung, kidneys, ovaries, and thyroid. The data in this case report was gathered via direct patient care and patient chart review. An 18-month-old previously healthy female was hospitalized for a newly diagnosed abdominal mass found on palpation during a well child evaluation. The ultrasound revealed a 9 cm cystic mass on the left kidney and the patient was subsequently sent to St. Jude Children’s Research Hospital. Further evaluation via CT scan has shown a large left renal mass that invaded the ureter and bladder, as well as enlarged lymph nodes in the left suprarenal space and a single 3mm right pulmonary nodule. At this time, cystic Wilm’s tumor was considered and the patient underwent a left radical ureteronephrectomy with lymph node sampling. Cytology report of the pelvic fluid had some inflammatory cells, but no tumor cells were seen in the sample. All of the sampled lymph nodes were also negative for tumor cells. The histological analysis of the mass revealed multiple cystic cavities separated by septa. No blastemal elements (WT1 immunostain was negative) or distinct solid areas were identified, which made the diagnosis of cystic Wilm’s tumor unlikely. The diagnosis of cystic nephroma (CN) vs cystic partially differentiated nephroblastoma (CPDN) is determined histologically by looking at the components of the septa – which, in this case, due to a marked inflammatory infiltrate expending the septa, made the morphology be more congruent with CPDN. Molecular testing of the tumoral tissue identified two DICER1 mutations (DICER1 frameshift mutation and DICER1 D1709E). Patient was subsequently diagnosed with Cystic Nephroma Stage I and further surveillance will be continued to monitor for more neoplasms associated with this mutation. This case highlights a rare disorder that predisposes patients to multiple neoplasms. Histology may not always be sufficient in determining the diagnosis, especially in differentiating CN from CPDN. Molecular evaluation may be helpful for the initial diagnosis and in order to provide adequate genetic counseling. Clinicians should be aware of DICER1 syndrome so they can adequately survey the at-risk patients for a range of benign and malignant neoplasms.

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