Leukemia Cutis in a Patient with Metastatic Pancreatic Cancer: A Case Report

Abstract

Background: Leukemia cutis is an extramedullary manifestation of leukemia with infiltration of neoplastic leukocytes into the epidermis, dermis, or subcutaneous tissues. Most often it is associated with myelodysplastic syndrome or acute myelogenous leukemia. Case History: Here we present a patient with new-onset, multiple, non-tender red papules, that were initially concerning for skin metastases of her previously diagnosed pancreatic ductal adenocarcinoma. She was previously diagnosed with pancreatic cancer six years prior and was in remission until one year prior when she was found to have pulmonary metastases. The metastatic pulmonary nodules were successfully treated with radiotherapy, and the patient was in surveillance prior to presenting with a two month history of rapidly growing pink nodules on her skin. Results: Skin biopsies initially indicated this was likely not metastatic pancreatic adenocarcinoma but rather a hematologic malignancy with monocytic blast dermal infiltration. A subsequent bone-marrow biopsy and staining indicated a second primary hematologic malignancy, acute myelogenous leukemia. With the patient’s previous chemotherapy history, this new malignancy could have been treatment related. However, genetic analysis revealed this was not likely as it did not harbor known phenotypes or markers of treatment related myelodysplastic syndrome or acute myelogenous leukemia including myelomonocytic leukemia with eosinophils (FAB M4EO) or an inversion in chromosome 16 (p13q22). Instead, cytogenetics and next-generation sequencing showed trisomy 8 and a gain of function missense mutation in U2AF1. Conclusion: Maintaining a broad differential and utilizing sequential diagnostic testing confirmed a blast phase de novo acute myelogenous leukemia, presenting as leukemia cutis. She was treated with decitabine and venetoclax and within a few days of initiation, her skin nodules had already begun to recede.