Mucinous tubular and spindle cell carcinomas are rare kidney tumors with generally indolent behavior. As the name suggests, classic histomorphology reveals bland spindle cells, tubules, and mucinous stroma. Uncommon histologic features include mucin-poor stroma, high nuclear grade, cellular pleomorphism, and presence of necrosis. Rare cases can show aggressive growth and distant metastasis. Mucinous tubular and spindle cell carcinoma has characteristic chromosomal abnormalities and the molecular signature remains the same, irrespective of the varied histomorphology.

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Introduction Juvenile myelomonocytic leukemia (JMML) is a rare childhood neoplasm (<5% cases), which has been categorized under myelodysplastic/myeloproliferative neoplasms (MDS/MPN) in the recent classification by the World Health Organization. Methods We developed a 51‐gene (151.5kB) low‐cost targeted myeloid panel based on single‐molecule molecular inversion probes to comprehensively evaluate the genomic profile of Juvenile myelomonocytic leukemia (JMML). Results A total of 50 children with clinical and pathological features of JMML were sequenced at high coverage. Among the 50 patients, 44(88%) harbored mutations in one of the RAS/MAPK‐pathway genes, most frequently in NRAS (32%), followed by PTPN11 (28%) and NF1 (22%). One‐fifth of children had more than one mutation, with 5 cases harboring two RAS pathway mutations. Monosomy 7 was detected in 32% (16) patients, and five of these did not harbor any RAS pathway mutations. Children with monosomy 7 showed shorter overall survival compared with their wild‐type counterparts (P = .02). Conclusion Our study highlights that comprehensive genomic profiling identifies at least one mutation in almost 90% of JMML patients. Performing genomic analysis at baseline might help in triaging children with JMML for allogenic stem cell transplant in resource‐constrained settings.