Dermoscopic features of a collision tumour composed of a pigmented basal cell carcinoma and a melanoma

The Usefulness of Dermoscopy for the Recognition of Malignant Collision Tumors

BACKGROUND

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.

METHODS

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.

RESULTS

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 (p < 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 (p < 0.001).

CONCLUSIONS

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.

Efficacy of Vismodegib in pigmented basal cell carcinoma: Appearances are deceiving

Basal cell carcinoma (BCC) is the most common skin cancer in humans. Pigmented basal cell carcinoma (pBCC) is a rare variant of BCC. Vismodegib, was the first drug to be approved for the treatment of locally advanced (laBCCs) or metastatic basal cell carcinoma. The aim of this study was to evaluate the efficacy of Vismodegib in patients with pBCCs. We retrospectively analyzed patients receiving Vismodegib as treatment for laBCCs presenting also various pBCCs. After 6 months of treatment, we performed excisional biopsies of pBCCs, that apparently at clinical and dermoscopic assessment did not respond to therapy. A total of nine patients were assessed. After 6 months of treatment, locally advanced target BCCs showed complete remission in four out of nine patients (44.4%), four patients (44.4%) were considered in partial remission and one patient (11%) showed no response to treatment. On the contrary, all the pBCCs showed both clinically and dermoscopically resistance to treatment. Therefore, clinically persistent pBCCs were surgically removed in three patients. Histology showed a complete elimination of the neoplastic cells together with features of previous regression. Our findings indicate that the efficacy of Vismodegib is higher than that documented by clinical or even dermatoscopic observation alone.

Colliding, colonizing or combining? Four cases illustrating the unique challenges presented by melanoma arising in conjunction with basal cell carcinoma

Biphasic lesions comprised of melanocytic and epithelial components are rare entities believed to arise either as a collision of 2 histologically distinct lesions in the same anatomic location or as a singular progenitor tumor differentiating along 2 differing lineages. Regardless of mechanism of origin, these tumors present unique challenges in pathologic interpretation and in determining appropriate measurements, which assigns subsequent prognosis to the patient. We present 4 tumors of melanoma co-existing with basal cell carcinoma (BCC) and discuss relevant literature regarding these biphasic entities. Patients consisted of 3 males and 1 female, ranging in age from 62 to 93, with lesions located on the shoulder, frontal scalp, forearm and nose. Three of 4 lesions showed melanoma cells limited to BCC tumor lobules, without evidence of direct dermal invasion by melanoma cells, raising the question of whether or not these tumors should be classified as in situ or invasive melanoma. These cases highlight the complexity that such lesions pose to dermatopathologists, in terms of their uncertain origin and variable microscopic appearance. In the absence of data regarding outcomes for these tumors (given their rarity), it is important to utilize a case-by-case approach, with careful clinical correlation and appropriate use of ancillary techniques.

Collision skin lesions-results of a multicenter study of the International Dermoscopy Society (IDS)

Background

Collision lesions as two independent and unrelated skin tumors often manifest an atypical morphology.

Objective

To determine the combinations of collision skin lesions (CSLs).

Methods

Twenty-one pigmented lesion clinics in nine countries included 77 histopathologically proven CSLs in this retrospective observational study.

Results

Seventy-seven CSLs from 75 patients (median age 59.8 years) were analyzed; 24.7% of CSLs were located on the head and neck area, 5.2% on the upper extremities, 48.1% on the trunk, and 11.7% on the lower extremities; 40.3% revealed a melanocytic component (median age 54.7 years), followed by 45.5% with a basal cell carcinoma (BCC) (median age 62.4 years) and 11.7% with a seborrheic keratosis (median age 64.7 years). CSLs with a BCC component were more often found on the head and neck area compared to tumors with a melanocytic component (34.3% versus 16.1%). Lesions with a melanocytic component were more often detected on the trunk compared to lesions with a BCC (64.5% versus 37.1%). Patients with CSLs with epidermal-epidermal cell combination were older than patients with epidermal-dermal cell combination (63 versus 55.2 years), were more often male than female (63% versus 43.3%), more often had the lesion on the head and neck area (32.6% versus 13.3%), and less often on the upper (2.2 % versus 10%) or lower extremities (8.7% versus 16.6%).

Conclusions

CSLs consist of a heterogeneous group of lesions of varying cell types. They are associated with advancing age and cumulative UV-exposure. CSLs manifest a complex morphology making it challenging to diagnose correctly.

Dermoscopic findings in a collision tumor composed of a dermatofibroma and a melanocytic nevus mimicking melanoma

Collision tumors consist of two different neoplasms occurring concurrently in the same lesion. This association has been described for both benign and malignant neoplasms that may be difficult to identify. Therefore, dermoscopy is a valuable tool to make a correct diagnosis. We report a very unusual collision tumor composed of both a dermatofibroma and a melanocytic nevus mimicking melanoma.

Melanoma in situ colonizing basal cell carcinoma: a case report and review of the literature

Colonization of basal cell carcinoma (BCC) by melanoma cells is a unique and uncommonly reported cutaneous entity. We describe a bluish nodule on the left forearm found during routine skin cancer surveillance examination with suspicious dermatoscopic findings including central-blue-white veil, sparse atypical dots, and a surrounding pink vascular blush with focal irregular tan-brown pigmentation at the periphery. Histopathology demonstrated a pigmented BCC with an overlying and adjacent melanoma in situ (MIS), as well as colonization of the BCC nodule by melanoma cells. We performed a review of the literature on the topic and discuss other presentations of cutaneous neoplasms composed of both BCC and melanoma, including collision, combined, and biphenotypic tumors. The prognostic and management challenges inherent to this distinctive neoplasm are summarized.