A 77-year-old Hispanic woman presented with a lesion of one-year duration that was progressively enlarging on her left breast; the lesion would occasionally bleed. Clinical examination showed a 2 x 1 cm black nodule; in addition, extending from the base of the tumor onto the adjacent skin, was macular brown pigmentation (Figures -). There was no palpable neck, axillary, or inguinal lymphadenopathy. The clinical differential diagnosis included a nodular malignant melanoma.\nA biopsy was performed. Microscopic examination showed that the lesion consisted of two concurrent tumors. The first was an ulcerated nodular basal cell carcinoma with aggregates of basaloid tumor cells extending from the epidermis into the dermis; there was pigment in both the tumor cells and within the melanophages in the adjacent dermis. The second was a seborrheic keratosis showing acanthosis and hyperpigmentation. Correlation of the clinical presentation and pathology established the diagnosis of a collision tumor consisting of an ulcerated nodular basal cell carcinoma and a seborrheic keratosis.\nMohs surgery was performed. The tumor was cleared in one stage. A layered closure was used to repair the surgical defect (Figures -). Follow-up after three months did not reveal any recurrence.
A 71-year-old male presented for a complete skin examination in November 2016. He had a history of actinic keratoses, a basal cell carcinoma, and a squamous cell carcinoma. He had new skin lesions on his nose.\nHis past medical history was significant for hyperlipidemia (treated with simvastatin) and coronary artery disease (and currently receiving clopidogrel).\nThe cutaneous examination was remarkable for 11 erythematous scaling plaques on his face and arms, consistent clinically with actinic keratoses. There is a 1 x 1 mm red dot surrounded by a 2 x 2 mm flesh-colored papule on his left nostril (Figures -). The lesion did not blanch when pressed with a glass microscope slide (Figure ).\nThe actinic keratoses were treated with liquid nitrogen cryotherapy. The lesion on his left nostril was biopsied using the shave technique. Microscopic examination of the lesion showed nodular aggregates of basaloid tumor cells extended from the adjacent epidermis into the dermis. There were also telangiectatic blood vessels in the papillary dermis (Figures -).\nCorrelation of the clinical presentation and pathologic findings of the nasal tip lesion was a red dot basal cell carcinoma (with nodular tumor aggregates). Excision of the tumor using the Mohs technique is planned.