The Usefulness of Dermoscopy for the Recognition of Malignant Collision Tumors

Abstract

<b><i>Background:</i></b> Preoperative diagnosis of malignant collision tumors (MCT) is extremely difficult. The value of dermoscopy to improve the correct detection of these tumors has not been previously studied. This study aims to evaluate the diagnostic accuracy of MCT with and without dermoscopy and to describe the dermoscopic features of a large series of MCT. <b><i>Methods:</i></b> Dermoscopic images of 161 MCT were evaluated. Clinical and dermoscopic images of histopathologically proven MCT intermingled with other tumors were randomly presented to clinicians with different levels of experience, blinded to the diagnosis and objective of the study. The clinical and dermoscopic diagnostic accuracies were measured separately. <b><i>Results:</i></b> A total of 161 histopathologically proven cases of MCT were collected. The most frequent MCT was basal cell carcinoma-seborrheic keratosis collision tumor (CT; 37.9%), followed by basal cell carcinoma-melanocytic nevus CT (19.9%), and melanoma-seborrheic keratosis CT (6.8%). Diagnostic accuracy among experts on dermoscopy was 71.4%. The study included 119 participants. The percentage of correct diagnoses was 8% by naked eye examination and 36.4% by dermoscopy (<i>p</i> < 0.001). The presence of the malignant component in the cases of MCT was not recognizable in 19.1% of cases by naked eye examination and in 11.8% of cases by dermoscopy (<i>p</i> < 0.001). <b><i>Conclusions:</i></b> The diagnosis of MCT can be assisted and clarified by dermoscopy. However, many of these lesions manifest complex morphologies and continue to be challenging, even for experts on dermoscopy. Atypical, uncertain, or non-classifiable lesions still need a complete excision for the final diagnosis.

Amelanotic Basomelanocytic Tumor

“…To our knowledge, about 50 cases of BMT have been reported in the literature [ 1 , 3 – 6 ]; dermoscopy has been described in details in only 9 cases ( Table 1 ). One of the two tumors is usually recognized upon dermoscopy when one of the two component is prevalent, but usually the exact diagnosis of BMT is difficult.…”

“…Zaballos et al recently found that the most frequent CTs are: basal cell carcinoma (BCC)-seborrheic keratosis (37.9%), BCC-melanocytic nevus (19.9%), and melanoma-seborrheic keratosis (6.8%). 1 The collision BCC-melanoma is very rare (reported under the terms "basomelanocytic tumor (BMT)") and its dermoscopic features have been described in only few cases [1,[3][4][5][6].…”

Skin collision tumour and dermoscopic diagnosis of melanoma in situ and dilated pore of Winer

“…In eight studies, triple associated lesion was reported (e.g. melanoma–BCC–trichoblastoma) 8 . Frequent tumours in photodamaged skin such as actinic keratosis and solar lentigo are probably underreported.…”

“…melanoma-BCC-trichoblastoma). 8 Frequent tumours in photodamaged skin such as actinic keratosis and solar lentigo are probably underreported. We present a new association of a DPW with MIS.…”

Cutaneous Squamomelanocytic Tumor: An Additional Case Report With Dermoscopic Features

“…The occurrence of squamous cell carcinoma and melanoma in the same tumor (SMT) is a rare event; Zaballos et al 2 recently found that the most frequent collision tumors (CTs) are: basal cell carcinoma–seborrheic keratosis (37.9%), basal cell carcinoma–melanocytic nevus (19.9%), and melanoma–seborrheic keratosis (6.8%). Histologically, CTs may result from a variety of modality of “collisions” such as colonization, combined, biphasic, biphenotypic, or intermingled neoplasms.…”