Basal cell carcinoma missed by deep shave biopsy: A sampling error

Abstract

An 85 year old Caucasian male with no history of immunosuppression presented with an asymptomatic bump on his left lateral neck which was present for several weeks. Physical examination revealed 1.0 cm × 0.8 cm flesh colored soft nodule associated with an underlying well healed scar on the left lateral neck. He had a nodular basal cell carcinoma (BCC) without any evidence of perineural invasion which was removed by a wide local excision with 4 mm margins in the area of the scar on the left lateral neck 14 months earlier. The results of that excision had revealed clear surgical margins. The area had healed well post operatively without any complications. Patient requested a biopsy of the bump because he was convinced that the bump represented a recurrence of his BCC. A deep frozen section biopsy of the bump was performed which revealed scar tissue with no evidence of any malignancy. The biopsy tissue from the frozen section was then submitted for permanent section processing in formalin which also showed the same diagnosis of scar tissue with no evidence of malignancy Patient was informed of the results but he insisted on having further resection of the lesion as he was still convinced that the lesion is cancerous. He then underwent a deeper excision of the same area which revealed basal cell carcinoma. Patient subsequently underwent Mohs micrographic surgery for more definitive treatment which required 3 stages. During the first stage of Mohs surgery, the top portion of the slide revealed only scar tissue and positive basal cell margin was at the very deep margin with only a small focus of tumor present. Subsequent Mohs stage revealed larger areas of basal cell carcinoma extending deeper into the neck tissue. This case illustrates that a negative skin biopsy report does not always rule out skin cancer. Clinical judgment and high index of suspicion especially in high risk individuals is essential in making accurate diagnosis of skin cancers. Relying solely on laboratory testing such as a skin biopsy slide alone may not be adequate and further tissue examination maybe necessary in cases of recurrent basal cell carcinoma.