SummaryExtravasation injuries are common in patients receiving multiple intravenous infusions. Although such injuries are closely associated with the infusion of cytotoxic chemotherapy, they have also been been associated with extravasation of noncytotoxic drugs. Extravasation injuries can lead to skin ulceration and nerve and tendon damage, and therefore to permanent disability. We report three cases of phosphate solution extravasation leading to unusual cutaneous manifestations.Extravasation injuries commonly occur in patients receiving intravenous (IV) infusions. There is a wide range of clinical responses to leakage of infusate, ranging from local irritation to necrosis and permanent damage leading to disability.1 Hypophosphataemia is associated with a range of medical conditions, including poor dietary phosphate intake, decreased intestinal absorption, increased urinary excretion and renal disorders.2 Most patients with hypophosphataemia are asymptomatic, although severe hypophosphataemia can lead to rhabdomyolysis, muscle weakness, cardiac arrhythmias and respiratory dysfunction.2 To our knowledge, there are no published reports of extravasation injury associated with IV phosphate replacement solutions. We present three cases of unusual cutaneous manifestations following IV phosphate solution extravasation. ReportPatient 1 was a 62-year-old woman, who was admitted to a medical ward following an episode of syncope. On admission, biochemical tests revealed profound hypophosphataemia and hypomagnesaemia. She was treated with a single infusion of IV phosphate and magnesium solutions (at a rate of 9 mmol over 12 h). During the phosphate IV administration, the IV access located in the patient's right antecubital fossa was dislodged, causing intense pain and localized erythema, followed by the development of a yellow plaque with central ulceration in the area of administration. On physical examination, a pale-yellow, indurated plaque with erythema and central ulceration was found on the right forearm, and smaller satellite lesions were present on the right forearm and right posterior forearm (Fig. 1a,b). An incisional biopsy, taken through the centre of the lesion, showed diffuse proliferation of fibroblastic spindle cells in the dermis, exhibiting a storiform arrangement and mainly lymphocytic dermal inflammation with multinucleated giant cells and areas of early mineralization (Fig. 2a,b). The patient was managed conservatively, and although the ulceration healed within a few weeks, the yellow indurated plaque persisted during the 6-month follow-up period.Patient 2 was a 69-year-old man, who underwent elective craniotomy for removal of a meningioma. In the postoperative period, peripheral vascular access was required for the administration of phosphate replacement solution (10 mmol over 6 h). The peripheral access line was dislodged during the administration, leading to the development within 2 weeks of a slowly expanding, yellow, indurated plaque (approximately 5 mm in diameter) on the dorsum of the patient's ...