Author: Dr Delwyn Dyall-Smith, Dermatologist, Wagga Wagga, NSW, Australia. DermNet NZ Editor-in-Chief: A/Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand. Copy edited by Gus Mitchell. September 2018.
Intralymphatic histiocytosis is a rare benign chronic skin condition most commonly associated with rheumatoid arthritis, orthopaedic metal implants, or cancer surgery. It was first described in 1994 as intravascular histiocytosis.
The exact cause of intralymphatic histiocytosis is not known. It was initially thought to be a reactive angiomatosis such as an early form of reactive angioendotheliosis. More recent theories include lymphatic disruption due to inflammation causing lymphatic vessels to dilate with pooling of lymph and poor clearance of antigens, resulting in an accumulation or proliferation of macrophages (histiocytes). A role for TNF-alpha has been postulated after two patients with rheumatoid arthritis were treated with infliximab, and the skin lesions resolved.
Intralymphatic histiocytosis has been classified as primary and secondary. Primary (or idiopathic) intralymphatic histiocytosis is where the patient has been otherwise well and no associated trigger can be identified. This is much less common than the secondary form where there is an associated condition, most commonly inflammatory or surgical.
The most common condition reported in association with intralymphatic histiocytosis has been rheumatoid arthritis, affecting over one third of reported cases. Osteoarthritis has also been reported, but less commonly.
Other conditions that have been reported once or twice in association with intralymphatic histiocytosis include:
Intralymphatic histiocytosis most commonly affects older adult females. In reported cases, it affects men and women as a rate of 3:5. The age range is 17 to 87 years, with a mean of 65.
Typically, intralymphatic histiocytosis presents as a rash on one limb overlying or adjacent to the affected joint or scar. It does not usually cause any symptoms. The colour ranges from red through brown and purple. It can be macular (completely flat) or may form a slightly raised plaque. Papules, nodules or vesicles may form. A linear or livedo pattern is sometimes seen.
The arm is the most common site that has been reported (in approximately 50% of cases), with the leg second most common. It has also been reported on the trunk, especially over a mastectomy scar, face, oral mucosa, and vulva.
There does not appear to be any correlation between the activity of the rheumatoid arthritis and the skin rash, but the rash does closely relate to an affected involved joint.
There is no pitting oedema or other signs associated with lymphoedema.
Biopsy is required to make the diagnosis. The histology of intralymphatic histiocytosis is diagnostic and requires the presence of dilated lymphatic vessels in the dermis with CD68 positive histiocytes within the lumen. The cells forming the lymphatic vessel wall and within the lumen are normal in appearance. Sometimes there may also be perivascular or granulomatous dermal inflammation of small lymphocytes, histiocytes and plasma cells.
Intralymphatic histiocytosis is usually resistant to all treatments that have been tried including topical, intralesional, and oral steroids. Temporary improvement may be seen but the skin disorder rapidly relapses.
Treatment of the associated condition may result in clearance of intralymphatic histiocytosis and has been reported after a joint replacement for an arthritic knee, antibiotics and tonsillectomy for tonsillitis, or antibiotics and surgical debridement of the vulval necrosis.
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