Noonan Syndrome: Common Molecular Alterations and the Consequences.

OBJECTIVES: Noonan syndrome (NS) is a relatively common autosomal dominant disorder with characteristic features and molecular alterations. The most common recurrent alteration is in the PTPN11 gene, a proto-oncogene that encodes a cytoplasmic receptor tyrosine phosphatase and helps regulate kinase activity and control cell survival and replication. Mutations in this gene can increase the risk for the development of multiple different malignancies, particularly hematopoietic. Here we present a case of NS with a PTPN11 mutation demonstrating the classic presentation of Noonan syndrome as well as the expected clinical follow-up.

Acute Myeloid Leukemia with t(8;16)(p11.2;p13.3)/ KAT6A-CREBBP in a Patient with an NF1 Germline Mutation and Clinical Presentation Mimicking Acute Promyelocytic Leukemia.

OBJECTIVES: Acute myeloid leukemia (AML) with t(8;16)(p11.2;p13.3)/KAT6A-CREBBP is an uncommon subtype of AML accounting for less than 0.5% of AML cases. AML with t(8;16)/KAT6A-CREBBP has characteristic clinical and pathologic features including disseminated intravascular coagulation (DIC), leukemia cutis, hemophagocytosis, monocytic or myelomonocytic differentiation, is frequently associated with therapy-related AML and has a poor prognosis. We present a classic case of AML with t(8;16)/KAT6A-CREBBP occurring in a patient with both a germline NF1 mutation and recent cytotoxic therapy for embryonal rhabdomyosarcoma.

Novel Cytogenetic Characterization of Pleomorphic Hyalinizing Angiectatic Tumor (PHAT).

OBJECTIVES: Pleomorphic hyalinizing angiectatic tumor (PHAT) is a rare soft tissue tumor that, despite its characteristic marked pleomorphism, is slow growing and of intermediate grade malignancy. PHAT is not known to metastasize, but is locally aggressive with a post-excision recurrence rate of up to 50%. Two other soft tissue tumors, hemosiderotic fibrolipomatous tumor (HFLT) and myxoinflammatory fibroblastic sarcoma (MIFS), share some morphological features with PHAT, and all three have been found to possess a t(1;10) translocation. Thus, it has been suggested PHAT, HFLT, and MIFS exist within a spectrum of a single entity; however, there is only one case of PHAT with a full cytogenetic profile and this showed the t(1;10). We report a case of PHAT with a complete cytogenetic profile differing from the previously reported case. Our case demonstrates 47,XY,+7,der(7)(qter::?::q31::?::pter::?::cen::?::pter::?::q31::?::qter)x2[20]/46,XY[10] karyotype with the typical morphologic features and immunohistochemical staining pattern seen in PHAT. This suggests that PHAT may be a distinctly separate entity and not within the spectrum of HFLT and MIFS.