Dermatoscopy: A nodule on a woman's leg.

Clinical presentation

A 61-year-old white female presented with a 7 × 4 mm nodule that was firm to palpation on her right leg (Figure 1) of 5 months’ duration. The lesion was not painful, but bleeding with minimal trauma.

Figure 1.

The lesion is located on the right leg, just below the right knee. It is an asymmetrical erythematous plaque with ill-defined borders. The pigmented area is attached to a palpable and ulcerated nodule. [Copyright: ©2015 Pigem et al.]

Dermoscopic appearance

The main findings were milky red-white areas, ulceration and atypical vessels on the palpable component and two pigmented areas at the periphery that were asymmetrically distributed (Figure 2).

Figure 2.

Asymmetry in its structures with a palpable area (right side of the picture) that presents atypical vessels and ulceration is seen. On the other side (left), adjacent to the nodule, a delicate pigmented area may be observed. [Copyright: ©2015 Pigem et al.]

What is your diagnosis?

Diagnosis

The lesion was totally excised to rule out malignancy with a final diagnosis of a compound tumor. The nodule with erosion and atypical vessels corresponded to an infiltrating basal cell carcinoma (Figure 3), whereas the firm area with pigmentation to a dermatofibroma (Figure 4).

Figure 3.

Compound tumor. The histopathologic analysis revealed an infiltrating basal cell carcinoma. Erosion is observed on the tumor surface (epidermis) and a tumoration of small basophilic cells forming micronodules and infiltrating cords with peripheral palisading surrounded by stroma is observed. There is also an inflammatory infiltrate (hematoxilin and eosin stain 10×). [Copyright: ©2015 Pigem et al.]

Figure 4.

Compound tumor. The other tumoral component of this lesion was a dermatofibroma. A not very well defined dermal tumoration of fusocellular cells with epidermal hyperplasia and hyper-pigmentation of the basal layer are seen (hematoxilin and eosin stain 10×). [Copyright: ©2015 Pigem et al.]

Discussion

A compound (collision) tumor is the result of two different neoplasms occuring in the same lesion. Correct diagnosis is important in order to offer proper treatment when benign and malignant lesions coexist. In the literature several compound tumors and their dermoscopic features, including the association between dermatofibroma and basal cell carcinoma, have been already reported [1]. Even though dermoscopy may be useful in the recognition of compound tumors, some cases may be more difficult to recognize. In the present case the main differential diagnosis was melanoma. Amelanotic/hypomelanotic melanoma is characterized clinically by the presence of asymmetry and ulceration, whereas irregular pigmentation and certain vascular patterns (milky-red areas and dotted and linear irregular vessels) are commonly seen in the dermoscopy of these tumors, similar to the present case [2].