images A and B demonstrate a pair of hands that are - narrow, long and thin skinned, with delicate tapering fingers. These features are called Eunuchoidal hand / Arachnodactyly and is seen in Marfan's syndrome, homocystinuria, hypogonadism, hyperthyroidism. Please note - it is also seen in normal individuals. The sign demonstrated in Image A is - Thumb sign Normally when a fist is made over a clenched thumb, the thumb should not extend beyond the ulnar side of the hand. Although in this case the hand is open and still the thumb easily crosses over to the ulnar side. The sign demonstrated in Image B is - Wrist sign In this sign, when the wrist is encircled by the thumb and little finger ( with light pressure / very little effort ), the little finger will overlap at least 1 cm. Differentials - Marfan's syndrome - Hypogonadism - Homocystinuria - Hyperthyroidism
