1. Mushroom - cloud sign of malignant melanoma

2. The ‘‘Bolognia Sign’’ was coined in reference to what Bolognia and colleagues initially described in 1994 as ‘‘small dark dots’’
near the periphery of a nevus
Subsequently, the use of dermoscopy has shown eccentric peripheral hyperpigmentation, defined as a single focus of darkest pigment greater than 1mm in diameter that touches the border of the lesion, to be a significant predictor of melanoma.
Under dermoscopy, this darker zone can appear as a brown or black structureless blotch, may contain thicker and darker peripheral network, and may demonstrate peripheral streaks.

3. Hofmann-Wellenhof and colleagues, in their 2001
dermoscopic classification of atypical nevi, concluded
that atypical nevi with eccentric hyperpigmentation
‘‘should be regarded as the most relevant simulators of melanoma within the morphologic spectrum of Clark nevus.’’

4. mushroom-cloud sign
the clinical and dermoscopic silhouette closely resembles a billowing smoke cloud from the detonation of a nuclear bomb.
the hyperpigmented area that has extended in one direction beyond the border of the lesion, and the plume underneath represents the stalk-like projection
We believe that this memorable term will be useful for
highlighting pigmented lesions that may warrant
closer attention.

5. well-known features of melanoma
specifically, asymmetry, irregular border, and multiple colors with the clinical concept of the explosive growth pattern of melanoma

6. Figure 1. Clinical (left) and dermoscopic images (right) of the mushroom-cloud sign in melanoma. (A) Malignant melanoma in situ, back. (B) Malignant melanoma in situ, interscapular back. (C) Malignant melanoma, Breslow depth 0.75 mm, right scapular back. (D) Malignant melanoma, Breslow depth 0.32 mm, left leg.

7. Figure 1. (A) Clinical image of an invasive melanoma, 0
Figure 1. (A) Clinical image of an invasive melanoma, 0.2mm thick on the left thigh of a 41-year-old woman. A light brownpapule with a regular border and an eccentric focus of darker brown hyperpigmentation localized in the left lower periphery of the lesion can be observed (original magnification, 10). (B) In the dermoscopic image of the same melanoma, irregularly distributed streaks at the edge of the lesion, that appear as a linear extension arising at the periphery of an atypical pigment network, can be recognized. An area of localized brown pigmentation asymmetrically distributed at the left lower periphery of the lesion can also be observed (original magnification, 10). (C) The histopathologic image of the same melanoma shows an atypical proliferative melanocytic lesion characterized by nests of junctional melanocytes arranged singly or in small groups and extending upward into the epidermis. A microinvasive component is seen in the papillary dermis as a small aggregate of atypical melanocytes. Scattered lymphocytes permeate the superficial dermis (original magnification, 400).