Myelodysplasia cutis is an emerging concept in cutaneous neoplasia. Many of these cases were previously included under the umbrella of histiocytoid Sweet syndrome. However, with the advent of next-generation sequencing, cutaneous involvement by myelodysplastic syndrome is being increasingly recognized.


To review histiocytoid Sweet syndrome and myelodysplasia cutis and discuss our current understanding of these entities. Additionally, to discuss how next-generation sequencing can be applied in the evaluation of cutaneous infiltrates of immature histiocytoid cells.

Data Sources.—

The English-language literature from 2005 to 2023 on the topic of histiocytoid Sweet syndrome and myelodysplasia cutis was reviewed.


Biopsy specimens showing infiltrates of histiocytoid, immature myeloid cells may represent cutaneous involvement by myelodysplastic syndrome. Close clinical correlation is recommended in these cases. Recent studies suggest that next-generation sequencing is useful in separating myelodysplasia cutis from true histiocytoid Sweet syndrome. This distinction has important implications for patients.

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Competing Interests

The authors have no relevant financial interest in the products or companies described in this article.

Author notes

Presented at the New Frontiers in Pathology Conference; October 26–28, 2022; Ann Arbor, Michigan.