Clinical-Dermoscopic-Histopathological Correlations in Collision Skin Tumours

Abstract

Objectives: Collision tumours are rare situations characterised by the coincidence of two different skin neoplasms in the same lesion.

Methods: We have analyzed 41 collision skin tumours from one department in the clinical-dermoscopic-histopathologic correlations.

Results: We present 41 collisions tumours. The mean age of our patients was 67.9 years, the mean diameter of the lesion was 11.6 mm. The most frequent locations were trunk (27 lesions) and head/neck (11 lesions). The collisions were classified as benign/benign (13 cases), benign/malignant (25 cases) and malignant/malignant (3 cases). The most frequent participants were seborrheic keratosis (24 cases), malignant melanoma (17 cases), melanocytic nevus (14 cases), basal cell carcinoma (12 cases) and heamangioma (10 cases). Thirty cases were of "dominant/minor" type and 11 cases of "half to half" type. Malignant tumours were a part of 28 collisions; these lesions were larger, patients were older and the malignant part was dominant in most cases. More than half of the collisions were unexpected by the initial clinical examination. Six collisions were missed by the initial histopathological examination.

Conclusions: Collision tumours can be missed by clinical or even histopathological examination. Dermoscopy is very helpful in the recognizing of difficult cases and cooperating with the histopathologist.

Keywords: Collision tumor; dermoscopy; histopathology; malignant melanoma.

Figure 1

(a) The collision of a seborrheic keratosis (left) and melanoma in situ (right) on the back of a 73-years old female patient, maximal diameter 18 mm. (b) The collision of a “half to half” type. Left (seborrheic keratosis): light brown parallel thick lines arranged in a cerebriform pattern. Right (melanoma in situ): dark brown reticular lines arranged in an irregular pigment network. (c) The part of acanthotic seborrheic keratosis on the left side; melanoma in situ on the right side (hematoxylin and eosin, ×100)

Figure 2

(a) The collision of a basal cell carcinoma (left) and melanoma in situ (right) on the trunk of a 76-years old male patient, maximal diameter 25 mm. (b) The collision of a “dominant/minor” type. Left (basal cell carcinoma – dominant part): pink ulcerated nodule with large hemorrhage and keratin structures, few linear branching vessels and blue ovoid nests (blue clods) at the periphery. Right (melanoma in situ – minor part): dark brown reticular lines arranged in a largely regular pigment network, few grey-brown dots. (c) Melanoma in situ in the epidermis; basal cell carcinoma in the corium (hematoxylin and eosin, ×100)

Figure 3

(a) The collision of a seborrheic keratosis (left) and basal cell carcinoma (right) on the face of a 63-years old female patient, maximal diameter 11 mm. (b) The collision of a “half to half” type. Left (seborrheic keratosis): a verrucous mass of yellowish color. Right (basal cell carcinoma): pink nodule with many linear branching vessels and one large blue ovoid structure (blue clod). (c) Seborrheic keratosis on the left side; basal cell carcinoma on the right site (hematoxylin and eosin, ×100)