Clinical and dermatoscopic diagnosis of early amelanotic melanoma

Abstract

Amelanotic cutaneous melanoma (ACM) often defies clinical diagnosis because of the lack of pigmentation. In an attempt to find diagnostic clues, we retrospectively studied the clinical features of 15 thin (< 1 mm thick or Clark level I) ACM lesions. The clinical features of early ACMs are identified and illustrated to enable early diagnosis and cure of these lesions. The typical early lesion presents as an asymmetric macula, which may be uniformly pinkish or reddish or, more often, has faint light pigmentation (tan, brown or grey) at the periphery; it has borders that may be well- or ill-defined. In our study, these features suggested the correct clinical diagnosis in only a minority (40%) of cases. Nine cases in this series were also subjected to dermatoscopy. By this technique we identified, as constant feature, the presence of small red dots, evenly distributed or grouped on a whitish or pink-red background. Our results show the importance of dermatoscopy in the evaluation of equivocal pink or reddish lesions. Red dots seen with this technique can be an important sign for the diagnosis of thin ACM. Since this sign does not appear to be pathognomonic, the presence of an associated pigmentary network can be decisive in the differential diagnosis.

Vascular Structures in Skin Tumors

“…Dotted vessels may be even more important when seen in amelanotic and hypopigmented melanomas, in which the diagnosis could be difficult because of the lack of pigmented structures. In these cases, dotted vessels can often be the only clue raising the suspicion for melanoma, as reported previously by Bono et al 17 In our study, the most common vascular pattern seen in melanoma was the linear-irregular typology (67.6% positive predictive value for melanoma), followed by dotted vessels and polymorphous/atypical vessels (Table 1 provides specific definitions of the 3 most frequent vascular patterns in melanoma). Although rarely seen, milky-red globules/areas showed the highest predictive value for melanoma (77.8%).…”

An Expression-Based Site of Origin Diagnostic Method Designed for Clinical Application to Cancer of Unknown Origin

“…Given also the histologic diversity of some carcinomas, we systematically represented histologic and molecular subtypes for some cancers [e.g., breast, ovarian, lung, gastric, and squamous cell carcinoma (SCC)]. Nonepithelial types, such as melanoma (22), seminoma (23), and mesothelioma (24), which can present with a cellular morphology and architecture indistinguishable from some poorly differentiated carcinomas, were also included. A summary of all tumors in the training set is detailed in Supplementary Table S6: Tumor classes.…”

Polymorphous Vascular Patterns in Dermoscopy as a Sign of Malignant Skin Tumors

“…In amelanotic skin tumors, polymorphous vascular patterns can be a sign of an amelanotic melanoma (case 1) [3, 4, 5, 6]. However, malignant nonmelanocytic skin tumors can also present polymorphous vascular patterns.…”

“…1b) was seen. Due to the polymorphous vascular pattern an amelanotic melanoma or a malignant epithelial skin tumor have to be excluded [3, 4, 5, 6]. Histopathology (HE) revealed a cutaneous melanoma with a tumor thickness of 0.8 mm and invasion level 3.…”

“…In addition, the accurate classification of reddish skin tumors as benign or malign is becoming more and more important as unnecessary excisions should be avoided. To prevent misdiagnosis, reddish tumors without a pigmented network, globules or streaks but with polymorphous vascular patterns must be considered malignant melanocytic or nonmelanocytic skin tumors [3, 4, 5, 6]. …”