"Apple Jelly" Sign: Diascopy in Cutaneous Sarcoidosis.

A 43-year-old woman presented with erythematous papules and plaques on the forehead evolving in the previous 3 months (Fig. 1). Diascopy, by showing a yellowish nodule-like aspect (Fig. 2), raised the hypothesis of cutaneous sarcoidosis, which was confirmed by histopathological examination. Sarcoidosis is a multisystemic granulomatous disease, a histologically evident characteristic shared by its cutaneous lesions. This granulomatous nature can be elicited by diascopy. The pressure from the glass slide application eliminates the characteristic erythema (Fig. 1), revealing a yellow-brown granulomatous appearance resembling apple-jelly (Fig. 2). Although not specific for cutaneous sarcoidosis, as it can also be seen on other granulomatous conditions such as granuloma annulare, this ‘apple jelly’ sign, classically described in association with sarcoidosis, can be a useful diagnostic tool. It is absent in the majority of sarcoidosis differential diagnosis, such as in lupus tumidus. Apart from its usefulness it also constitutes a curious clinical picture.1,2