Blue scales on an “iced” scalp

Abstract

Although the diagnosis of actinic keratosis (AK) is mainly clinical, dermoscopy is a highly useful and accurate diagnostic technique. The dermoscopic features of AK include the strawberry pattern with white areas, keratotic, follicular openings, a pseudonetwork, and rosettes [1]. An 82-year-old male with a personal history of type 3 autoimmune polyglandular syndrome and hypertension was referred to the dermatology department due to the presence of scaly lesions located on the scalp and forehead. A physical examination revealed asymptomatic, keratotic lesions on the forehead and in the occipital region (Fig. 1a). The patient denied the application of any product except toning shampoo for white hair. Interestingly, the lesions had a blue, superficial scale, although they clinically resembled AK. Dermoscopy evidenced an erythematous background with multiple, arctic-blue, keratotic plugs (Fig. 1b). Moreover, a superficial excision of one of the lesions was performed, evidencing solar elastosis and a chronic dermal infiltrate, as well as basal keratinocytes with loss of polarity, presenting with irregular nuclei (Fig. 2). Thus, the clinical and pathological correlation confirmed the diagnosis of AK. The lesions were treated with cryotherapy leading to their resolution. Figure 1: (a) Clinical presentation of the cutaneous lesions: numerous bluish-gray, scaly lesions in the occipital area; the patient confirmed using toning shampoo for white hair containing Acid Violet 43. (b) Dermoscopy of one of the lesions: an erythematous background, as well as numerous arctic-blue, keratotic plugs; the blue scale compatible with the iceberg sign present in AK neglecta. Figure 2: Solar elastosis and a chronic dermal infiltrate, as well as basal keratinocytes with loss of polarity presenting with irregular nuclei; findings compatible with the clinical suspicion of AK; no basophilic amorphous material present in the stratum corneum (H&E, 20×). Blue AK has been termed AK neglecta while the dermoscopic blue coloration the iceberg sign [2,3]. The latter is described to be caused both by sunscreens containing titanium dioxide [3] or shampoos containing Acid Violet (present in the shampoo that the patient used) [2]. Moreover, this exogenous pigmentation may easily be removed with alcohol [3]. Histologically, a basophilic amorphous material on the stratum corneum is described to be present [2]. A lack of this finding in our case might have been explained due to the 10% formol used to preserve the biopsy, eliminating the pigment. Recognizing this presentation is essential due to the widespread use of toning shampoos and sunscreens among the elder population.