Track

Abstract

Intralymphatic histiocytosis (ILH) is a rare histologic feature characterized by the presence of histiocyte collections within lymphatic vessels.  Clinically, the finding of ILH shows considerable variability, ranging from localized to disseminated lesions, with morphologies including livedo-like erythema to indurated nodules and plaques. ILH has been associated with a variety of disease processes, most notably rheumatoid arthritis (RA). It has also been reported in association with inflammatory bowel disease, metallic joint prostheses, osteoarthritis, bacterial infection, and other conditions. We present three patients with distinct ILH presentation: (1) a 67-year-old woman with RA who presented with a localized wrist eruption, (2) a 74-year-old man with a persistent papulonodular eruption of the shoulder and chest following arthroplasty; and (3) a 54-year-old man with Crohn’s disease and lower lip swelling. Microscopically, each case demonstrated collections of histiocytes within lymphatics, supported by immunostains.  From a review of >60 cases in the published literature, we observed a range of histopathologic features, including variation in intravascular cell composition, vessel morphology, perivascular infiltrates, and associated stromal changes. We noted increased perivascular fibrosis and endothelial hyperplasia in cases with greater clinical chronicity, including those secondary to arthroplasty and joint replacement; increased perivascular aggregates of lymphocytes and plasma cells were more frequently observed in RA and other joint disease-related cases; dermal edema and perivascular granulomas appear more frequent in cases associated with Crohn’s disease. These findings underscore the clinical and microscopic heterogeneity of ILH and highlight its occurrence across diverse clinical settings.