# Blastic Plasmacytoid Dendritic Cell Neoplasm: A Case Report

## TL;DR

This case report describes a rare blood cancer called blastic plasmacytoid dendritic cell neoplasm in a 64-year-old woman, highlighting its aggressive nature and diagnostic features.

## Contribution

The report contributes a detailed clinical case of a rare neoplasm with specific diagnostic findings and disease progression.

## Key findings

- The patient presented with a skin mass that was confirmed to be blastic plasmacytoid dendritic cell neoplasm.
- Bone marrow analysis and flow cytometry confirmed CD4+ and CD56+ neoplastic precursor cells.
- The disease is associated with deletions in tumor suppressor genes like RB1, CDKN1B, CDKN2A, and TP53.

## Abstract

A rare condition, blastic plasmacytoid dendritic cell neoplasm, is classified as acute myeloid leukemia–related precursor neoplasms according to the World Health Organization’s 2022 classification. Previously thought to originate from natural killer cells, T cells, or monocytes, it is now believed to arise from plasmacytoid dendritic cells. The cause of this condition is not well understood, but it is often associated with the deletion of tumor suppressor genes such as RB1, CDKN1B, CDKN2A, and TP53.

The disease is aggressive and typically presents with initial cutaneous lesions that can progress to bone marrow involvement and leukemic dissemination. Flow cytometry/ immunohistochemistry can detect enhanced CD56, CD4, and CD123 expression. The differential diagnoses include myeloid sarcoma/acute myeloid leukemia, T-cell lymphoblastic leukemia/lymphoma, NK-cell lymphoma/leukemia, and certain mature T-cell lymphomas/leukemias. Although initial chemotherapy may elicit a patient response, relapse is common. Survival may be improved by stem cell transplantation.

This case report details the medical history of a 64-year-old woman who presented with a skin mass that exhibited slow growth over 6 months. The mass was firm on palpation. Extensive testing, including a bone marrow (BM) smear and biopsy, revealed numerous abnormal or blastic cells. Furthermore, flow cytometric analysis of the BM confirmed the presence of plasmacytoid dendritic cell–neoplastic precursor cells exhibiting CD4+ and CD56+ characteristics.