Fatal foreign-body granulomatous pulmonary embolization due to microcrystalline cellulose in a patient receiving total parenteral nutrition: all crystals are not what they seem

Pulmonary foreign-body granulomatous embolization has been described secondary to crystal precipitation in total parenteral nutrition (TPN) as well as when pharmaceutical tablets are crushed and injected intravenously. Extensive granulomatous embolization may cause pulmonary hypertension and death due to acute cor pulmonale. We report the case of a 34-year old woman who had been receiving TPN post-operatively secondary to complications of a paraesophageal hernia repair. During and following receiving TPN, she experienced episodes of hypoxia, tachycardia, fever, and hypotension. Computed tomography scans of the thorax showed centrilobular nodules, tree-in-bud and ground-glass opacities, as well as findings of pulmonary hypertension. Following an episode of hypoxia she was found unresponsive and died despite resuscitative efforts. Microscopic examination of the lungs following post-mortem examination revealed occlusive granulomatous inflammation of the pulmonary arterial vasculature by crystalline material. The morphologic and histochemical patterns of the crystals were suggestive of microcrystalline cellulose, a finding that was confirmed by energy dispersive X-spectroscopy and infrared spectroscopy. Ancillary tests did not support that the crystalline material was the result of TPN precipitation. Foreign-body granulomatous embolization leading to acute core pulmonale may occur as a complication of both intravenous injection of oral medications as well as of TPN crystallization. The source of crystalline material may be difficult to discern based solely on morphological assessment or by histochemical staining. Ancillary studies such as energy dispersive X-spectroscopy or infrared spectroscopy should be performed to definitively discern the two entities.