A clinical diagnosis of lentigo maligna at an early stage is often difficult even for experienced dermatologists. Differential diagnoses would include solar lentigo, early lesions of seborrheic keratosis, lichen planus-like keratosis, pigmented actinic keratosis and melanocytic nevus. Dermoscopy has been shown to have higher diagnostic accuracy, especially in the diagnosis of pigmented skin lesions, in the past two decades. To aim of the present study was to review the diagnostic key points on dermoscopy in the published work to differentiate lentigo maligna from other differential diagnoses and reassess these important features on dermoscopy for specificity by describing the findings in detail. Diagnostic key points for lentigo maligna/lentigo maligna melanoma on dermoscopy are asymmetrical pigmented follicular openings, rhomboidal structures, annular-granular structures and gray pseudo-network. Lentigo maligna, at first, seems to occur as asymmetrical pigmented follicular openings and/or annular-granular structures, then expand and develop into the rhomboidal structures. Annular-granular structures and gray pseudo-network seem to be observed also in regressive areas of solar lentigo/initial seborrheic keratosis, lichen planus-like keratosis and pigmented actinic keratosis. The four important criteria on dermoscopy for the diagnosis of lentigo maligna have been reviewed, and the former two criteria seem to be more specific, but it might be difficult to recognize these findings without misinterpretation. The latter two seem to be not so specific as they would also be demonstrated in other pigmented epidermal lesions, although the distribution of the structures in these disorders would be inclined to be more homogeneous than that of lentigo maligna.

Dermoscopic findings for 17 cases of lichen planus-like keratosis (LPLK) were chronologically evaluated. Three males and 14 females were included in the study and the ages ranged from 43 to 85 years (median 65 years). Three cases were diagnosed based on stereotypical dermoscopic findings, while the other 14 cases were histopathologically diagnosed as LPLK. Dermoscopy photographs were divided into four groups depending on the number of days (D) from the initial visit: 1) D = 0 (initial visit or biopsy day); 2) D = 61 to 180; 3) D = 181 to 270; 4) D = 271 to 360. Dermoscopic findings, described as light brown pseudonetwork, pinkish area, gray pseudonetwork, annular granular structures, and blue-gray fine dots, were evaluated at every visit to the hospital.Initial dermoscopy features included light brown pseudonetworks due to residual solar lentigo and overlapping pinkish areas attributed to lichenoid inflammation. Annular granular structures and gray pseudonetwork appeared to be the main features of the regressing stage; these features seemed to progress to “blue-gray fine dots” in the late regressing stage. Blue-gray dots or globules reflecting melanophages, the hallmark dermoscopic features of LPLK, were believed to resolve in approximately one to two years. Based on the clinical and dermoscopic observations, we have specified five stages of evolution of LPLK, namely 1) pre-existing solar lentigo, 2) early inflammatory stage, 3) early regressing stage, 4) regressing stage, and 5) late regressing stage.The limitations of the study are that this is a small-sized, retrospective, observational study and that ethnicity of participants is limited to Japanese patients with skin phototype III.

Eccrine porocarcinoma is a rare cutaneous neoplasm that mainly affects elderly people and grows slowly over a long period of time but often experiences an accelerated growth phase. Eccrine porocarcinoma may arise de novo or evolve from a pre-existing benign eccrine poroma. We reported a 86-year-old Japanese woman presenting with two reddish-colored pendulated lesions on a keratotic light brown plaque on the right thigh. Dermoscopic examination of the light-brown plaque demonstrated many whitish globular structures in a light-brown background. At the two reddish-colored pendulated lesions, polymorphous and prominent vessel proliferation was observed together with irregularly shaped whitish negative network. Immunohistochemical study demonstrated a positive CEA staining at ductal structures and atypical clear cells of reddish nodules. A diagnosis of eccrine porocarcinoma arising in a pigmented hidroacanthoma simplex was eventually established, and the dermoscopic features of eccrine porocarcinoma from hidroacanthoma simplex was described for the first time.

The accuracy of our method was competitive or better than five recently published methods. Our new method is the first method for detecting borders of both non-melanocytic and melanocytic skin lesions.

A 63-year-old healthy female patient presented with well defined itchy erythematous lesions on the area of her eyebrows. Her eyebrows had been tattooed two months before her visit to us. The lesions had previously been treated by application of steroid ointment and anti-histamine and steroid tablets by mouth without success. We suspected the lesions to be contact dermatitis caused by some metal element contained in the dye used for tattooing. Treatment was continued for two weeks, but the lesions spread to her cheeks and forehead. No fungal element was found from the lesions by direct microscopy at this stage. The patch-testing to 20 metal substances on her skin showed no allergic reaction. After one more week of treatment, we reexamined the scale taken from the lesions by direct microscopy, and fungal elements were found at that time. Microsporum (M.) gypseum was isolated from the scale taken from the lesions. The lesions cleared after treatment of 11 weeksoral intake of itraconazole 100 mg daily. It was found that the patient was accustomed to sleep with her dog, a Chihuahua. On examination by a veterinarian, no skin lesions were found on the dog. We speculate that the paws of the dog might have carried soil contaminated by M. gypseum, a geophilic fungus, to the area of her eyebrows which had minor trauma after being tattooed.