Linear Pigmented Basal Cell Carcinoma: Exceptional Clinical Entity with Rare Localization

Keywords

Basal Cell Carcinoma; Linear; Pigmented; Shoulder; Rare Localization.

Introduction

Basal cell carcinoma (BCC) is the most common human malignancy, and accounts for nearly 80% of all non melanoma skin cancers [1] Several morphologic and histologic variants of BCC have been reported [2]. Linear pigmented basal cell carcinoma is a distinct and rare morphological variant. The first case was described by Lewis in 1985, and since then only 37 cases have been reported [3]. The most common site is the periorbital region [4], especially the lower eyelid and malar region, and they were followed by cervical and trunk. The main of our case is to report a new case of linear pigmented basal cell carcinoma developed in the shoulder, which is a rare localization.

Observation

A 57-year-old man with no pathologic history had a linear pigmented lesion with onset 1 year earlier, on the right shoulder. The patient reported the notion of manipulation of a papule at the same site before the symptomatology. Clinical examination found a linear pigmented plaque measuring 4 cm, well limited, with erosions and crusts at its center (Figure 1). The differential diagnosis was essentially linear angiokeratomas. Dermoscopy revealed ovoid nests, a peripheral digitiform aspect, telangiectasia and arborizating vascularization and central ulceration, with no pigmented network (Figure 2). The diagnosis of pigmented basal cell carcinoma was confirmed by histology, which showed tumor proliferation of basaloid cells, arranged in palisaded cords, basophilic and sometimes pigmented cytoplasm, and retraction slits. Surgical excision with margins was performed, with histological study concluding a nodular and pigmented basal cell carcinoma, with healthy margins. No recurrence had occurred after 2 years of follow up (Figure 3).

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Figure 1:

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Figure 1. Pigmented plaque with a linear arrangement on the right shoulder.

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Figure 2:

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Figure 2. Dermoscopy: ovoid nests, a peripheral digitiform aspect, telangiectasia central ulceration.

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Figure 3:

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Figure 3. Clinical and dermoscopic control of the exeresis scar.

Discussion

Our case describes a rare form of linear pigmented basal cell carcinoma, with the same features reported in the literature. Nevertheless, the most frequent localization described was the periorbital region [4]. The location at the shoulder is exceptional. The majority of linear CBCs are oriented along the lines of tension of the skin, this linear arrangement can be explained by several mechanisms, including the koebner effect, as the case of our patient [5]. Dermoscopy is used to guide the diagnosis of CBC with ovoid nests, ulceration and telangiectasia. The diagnosis is confirmed by histology and nodular CBC represents the most reported histologic subtype. The orientation along the tension lines allows easy surgical excision with good healing. However, the lateral extension of the tumor requires excision with margins of safety.

Acknowledgement & Declarations

All authors contributed to the writing of this article. The authors also state that they have read and approved the final version. The authors declare no conflict of interest.

Conclusion

Pigmented and linear basal cell carcinoma is a rare morphological variant whose clinical, topographical and therapeutic characteristics must be known. Hence the interest of dermoscopy which has made it possible to correct the diagnosis allowing adequate management.