Measurement of the Heel-Pad as an Aid to Diagnosis of Acromegaly

Acromegaly is an insidious disease affecting all tissues of the body, not all, however, to the same extent. The involvement varies in different patients, probably the result of individual genetic make-up and the variable response of tissues to the stimulus of excessive growth hormone. Another factor may be the extent of imbalance of various hormones caused by the expanding lesion in the sella turcica. In general, the response of the tissues is one of hyperplasia and hypertrophy. The size of the bones may increase because of an accelerated endochondral ossification or appositional bone growth. In a previous investigation of the roentgen features of acromegaly (1), the most constant feature noted was an increase in thickness of the soft tissues of the fingers, toes, and scalp. This thickening diminished slightly after successful irradiation or surgical removal of the pituitary gland, but the tissues did not revert to normal size. The thickening of the skin is caused primarily by increased connective tissue, but other elements including epithelium and the hair follicles are also increased in size. The subcutaneous tissues become greatly thickened and an unusual type of edema produces additional swelling. The soft-tissue thickening, particularly well demonstrated between the calcaneus and the plantar surface of the foot, is readily measured on roentgenograms. Since the part measured is close to the film, only minimal distortion occurs. Slight changes from the true lateral position do not significantly alter the measurements. The radiation dose necessary for these roentgenograms is minimal and distant from the gonads. The cost is not great, as a single small lateral view of the heel is all that is required. Therefore, a determination of the range of thickness of the normal heel-pad and a comparison with thicknesses of heel-pads in acromegaly were undertaken. Method Skeletal surveys have just been concluded of normal relatives of patients with rheumatoid arthritis. Lateral roentgenograms of the feet of 46 males and 57 females were included (Fig. 1). Since acromegaly is a disease of late adolescence and adult life, heel-pads were studied only in persons more than seventeen years old. The ages ranged from seventeen to eighty-eight years. Lateral roentgenograms of the feet were obtained at a focal spot-film distance of 40 in., cardboard film-holders without grids or intensifying screens being used. No correction was made for distortion. The shortest distance between the calcaneus and the surface of the skin was measured (Fig. 2). Twenty-nine patients with unequivocal clinical and laboratory evidence of acromegaly were similarly studied. In most of these the sella turcica was enlarged from a pituitary neoplasm, but some were normal in appearance. The sella had been previously irradiated in 20 patients, and in 1 of these, irradiation was followed by hypophysectomy.