Synchronous clonally related anaplastic large cell lymphoma and malignant histiocytosis.

Background: Synchronous malignant histiocytoses are rare conditions that occur concurrently with another hematologic neoplasm. Most reported cases are associated with B-cell lymphoproliferative disorders, while associations with T-cell hemopathies are less common. These two diseases may share mutations and/or cytogenetic anomalies, which can lead to malignant proliferations.