Focal lung uptake of technetium 99m methylene diphosphonate associated with pulmonary emboli and hypercalcaemia

Extraosseous accumulation of 99Tcm phosphate radiopharmaceuticals has been reported in a wide variety of conditions during the decade since these agents came into widespread use for bone scintigraphy (Brill, 1981). The following case includes a previously unpublished cause of such an abnormality and may throw further light on the mechanisms involved. A 47-year-old woman was referred for a bone scintigram to investigate possible osseous metastases associated with hypercalcaemia. Three weeks previously she had presented to another hospital with exhaustion due to severe anaemia (Hb 4.9 g/dl). She was found to have an advanced squamous carcinoma of the cervix confirmed by biopsy at examination under anaesthetic. While arrangements for radiotherapy treatment were being made she developed leg oedema and a clinical diagnosis of deep vein thrombosis was made. She had no respiratory symptoms and no abnormal signs on examination of the chest. Chest X ray on 18.10.81 (Fig. 1) was normal. Serum calcium on 19.10.81 was 3.75mmol/l (normal range 2.2–2.6). The bone scintigram, performed on 21.10.81, four hours after injection of 550 MBq to 99Tcm methylene diphosphonate, showed no definite evidence of osseous metastases but there was soft tissue uptake of tracer at the base of the left lung and a less well-defined area of abnormal uptake in the left upper zone posteriorly (Fig. 2). A lung scintigram (99Tcm albumin microspheres) carried out the following day, showed perfusion defects involving the posterior segment of the left upper lobe and most of the left lower lobe except the apical segment (Fig. 3a).