# Leukaemia cutis as a late, isolated extramedullary relapse: a case report of a patient with acute myeloid leukaemia 6 years after allogeneic bone marrow transplantation and remission

## TL;DR

A patient with a history of acute myeloid leukaemia experienced a rare skin-only relapse 6 years after a successful bone marrow transplant.

## Contribution

This case report presents a rare instance of isolated leukaemia cutis as a late extramedullary relapse after allogeneic bone marrow transplantation.

## Key findings

- A 24-year-old male developed leukaemia cutis 6 years post-transplant with no systemic or bone marrow involvement.
- Local radiotherapy was effective for treating the isolated skin relapse.
- The case emphasizes the need for long-term monitoring for late extramedullary relapses in leukaemia survivors.

## Abstract

Leukaemia cutis (LC) is characterized by the infiltration of leukaemic cells into skin tissue, presenting as various skin lesions. It can signal relapse or coexist with extramedullary or systemic relapses. Extramedullary relapse, particularly in sanctuary sites like the skin, remains a clinical challenge, demanding investigation into mechanisms and monitoring strategies. We present a unique case of isolated extramedullary relapse manifesting as LC, 6 years after successful allogeneic bone marrow transplantation for acute myeloid leukaemia. A 24-year-old man exhibited a cutaneous nodule on his scalp, prompting comprehensive evaluation. Despite achieving complete remission post-transplantation, a core needle biopsy confirmed LC. Extensive assessments, including blood tests and bone marrow biopsy, returned normal results. As the disease was confined to skin, the patient received local radiotherapy. This case instead highlights the overall challenge of detecting and treating late, isolated extramedullary relapse.

Leukaemia cutis (LC) occurs when leukaemic cells infiltrate the skin, signalling relapse or coexisting with systemic disease. Extramedullary relapse, particularly in sanctuary sites like the skin, presents a clinical challenge. We report a rare case of isolated LC relapse 6 years post-allogeneic bone marrow transplant for acute myeloid leukaemia. A 24-year-old male developed a scalp nodule, which biopsy confirmed as LC, despite normal blood and marrow results. He received local radiotherapy. This case highlights the need for prolonged vigilance and research to improve post-transplant relapse detection and management.