An atypical pigmented lesion on the nose-Answer.

Below find the answer and discussion to the quiz by Savoia et al. presented in the previous issue of Dermatology Practical & Conceptual (http://dx.doi.org/10.5826/dpc.0401a12).

Diagnosis

Pigmented cutaneous squamous cell carcinoma (PCSCC).

Clinical course

The patient had no evidence of local recurrence or metastasis during 12 months of follow-up.

Answer and explanation

PCSCC is a variant of invasive squamous cell carcinoma, with less than 20 cases reported, to our knowledge, in the English literature [1,2]. PCSCC had been more often reported to occur in the oral mucosa and conjunctiva [3]. Pigmentation is probably due to cytokines secreted by tumoral cells that stimulate melanocytes to produce melanin [4]. In some cases, PCSCC may be the malignant progression of a pigmented actinic keratosis or a pigmented Bowen’s disease [4].

The clinical appearance of PCSCC is considered non-specific, with differential diagnoses including other benign and malignant skin lesions such as melanoacanthoma, seborrheic keratosis, melanoma, pigmented basal cell carcinoma, pigmented basosquamous carcinoma and pigmented adnexal tumors [3,5].

The dermatoscopic features of our case were unspecific and no algorithm was useful for a correct diagnosis [6,7]. As previously reported by Rosendahl and colleagues, malignancy was considered on the basis of the “chaos and clues” algorithm: there was “chaos” (asymmetry, structureless global pattern) and the clues of “few discrete blue-grey blotches with rather ill-defined edges (blue)” and “atypical vessels” [6,7]. Indeed, the scaly center and the pink-white halo were suggestive of a keratotic lesion, even though the diagnosis of PCSCC was not initially considered.

On the basis of our and previous reports, PCSCC should be considered when dealing with a pigmented lesion characterized by an unspecific dermoscopic pattern with the features of diffuse blue-gray pigmentation, scaling, polymorphic vessels and radial structures [1,6,8,9].

Congratulations to Dr. Paschal Dsouza, who was the first to send us the correct answer!