Abstract:

Intralymphatic reactive histiocytosis (IRH) is a rare, reactive skin condition, that may present as poorly demarcated erythematous plaques, livedo reticularis-like lesions, papules, vesicles, or nodules. These lesions are largely asymptomatic and may vary widely in appearance. IRH may be primary/idiopathic or secondary to an underlying condition. The condition was first described in 1994 and was referred to as “intravascular histiocytosis” until D2-40 staining by Okazaki et al in 2005 proved the intralymphatic nature of the condition. IRH seems to occur mostly in adult or elderly patients, and often in proximity to an inflamed joint of the extremities. Rheumatoid arthritis (RA) is the most common condition associated with IRH. Other known associations include osteoarthritis, as well as orthopedic metal implants from joint replacements or repairs after fractures. Some cases of IRH have resolved after joint replacement or treatment of RA. It has an indolent and chronic course, and no therapy has shown evidence of complete efficacy. We report a case of IRH in a 63-year-old male who presented with erythematous and indurated reticular plaques overlying his left shoulder and upper arm, present for several months though asymptomatic. Histopathological interpretation of a lesional cutaneous punch biopsy specimen revealed dilated vascular spaces that stained positively with CD34 and D2-40 and contained mononuclear cell nodular sheet-like aggregates filling the vessel lumens. Immunohistochemical analysis revealed the intravascular mononuclear cells to stain strongly for CD68 in approximately 80% of the intravascular aggregates. Tissue flow cytometry was unrevealing for hematolymphoid malignancy with no aberrant or monoclonal T-cell or B-cell population identified. Further workup was negative for RA but did show osteoarthritis of the left shoulder. As the lesion was asymptomatic, no further treatment was pursued.

Financial Disclosure:
No current or relevant financial relationships exist.

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Kate Zipperer, BSA