Intravascular histiocytosis: mimicker of cellulitis, angiosarcoma, inflammatory breast cancer, and others.

Background: Intravascular histiocytosis is an underrecognized reactive skin condition characterized by the clinical finding of poorly demarcated erythematous to violaceous patches and plaques. The diagnosis is confirmed by the histologic findings of intraluminal histiocytes on skin biopsy and exclusion of an alternative diagnosis.

Methods: A review of patients with a histologic diagnosis of intravascular or intralymphatic histiocytosis and seen at Mayo Clinic, Rochester, Minnesota, from January 1, 2010, to October 10, 2020, was performed. Histologic and clinical information was collected from the medical records.

Results: Nine patients were identified. Clinical impressions prior to biopsy varied widely, and no clinician included intravascular histiocytosis in the initial clinical differential diagnosis. Eight patients had preceding trauma to the affected area.

Conclusion: Intravascular histiocytosis remains a rare skin condition. Clinical identification remains low. Our cases add support to the hypothesis that intravascular histiocytosis is a reactive condition often preceded by trauma and/or surgery.