Crystals in intravenous drug users (IVDUs): Examination of the lung sections of this patient with polarized light showed deposits of foreign crystals. The crystals are deposited in arterioles and capillaries but may erode through the vessel wall into the interstitium. In some cases granulomas and fibrosis develop.

A. This photo taken with polarized light shows birefringent crystals (bright spots) in the lung of the patient. Numerous, scattered crystals up to 40 µm long were located mainly in the interstitium. A few foreign-body giant cells were present, but granulomas and scar were absent.

B. Similar crystals were found in macrophages in the portal triads of the liver shown here. Most were less than 10 µm long, as these crystals had traversed the pulmonary capillary bed. A granulomatous response was absent. Crystals were also found in the spleen.

Effects of injection of oral medications: IVDUs sometimes inject intravenously drugs that are intended for oral use. The tablets are ground to a powder and dissolved in water before injection. Tablets, including tripelennamine (Pyribenzamine), methadone, methamphetamine (speed), and methylphenidate (Ritalin), contain fillers of talc, microcrystalline cellulose, or starch. These particles are trapped primarily in the pulmonary vasculature, but some particles less than about 5 µm in diameter traverse the capillary bed. As a result of systemic spread, the crystals may be viewed in the microcirculation of the retina ophthalmoscopically. The crystals do not interfere with visual acuity or other organ function. Pulmonary effects may include fibrosis, emphysema, or hypertension [1].


1. Paré J, Fraser R, Hogg J, Howlett J, Murphy S. Pulmonary 'mainline' granulomatosis: talcosis of intravenous methadone abuse. Medicine 1979; 58:229-239.

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