Basal cell carcinoma and basosquamous carcinoma, two faces of the same condition?

Basal cell carcinoma (BCC) is the most common locally invasive malignant epidermal neoplasm. It is generally a tumor that runs a slow progressive course and can usually be cured by surgery. Basosquamous carcinoma is considered by some authors a rare subtype of BCC, while others describe it as independent tumor with different evolution from BCC. The aim of the study was to present a very interesting case of initially otherwise ordinary BCC that during its repeated and extensive relapses changed its histopathology in a basosquamous carcinoma, despite the free surgical margins and leading to major surgeries with loss of right eye. We present a case of 75-year-old male diagnosed in 2008 with a tumor located in the right naso-orbital region. The patient underwent surgical treatment, the histopathology being consistent with BCC. He presented recurrences of the tumor in 2009 and 2010 that were excised at approximately 9 and 16 months, respectively, from the first intervention. In 2010, the surgical procedure was radical, with removal of the tumor and the entire right superior eyelid. This approach proved to have negative side effects over the right eye in time. Therefore, after two months, a complete exenteration of the right orbit was necessary. The tumor recurred again for three times, after 20, 30 and 42 months from the first intervention and every time surgical treatment was applied. The microscopic inspection of the biopsies showed similarities between recurrences and initial tumor. In 2013, after 57 months from the first intervention, the patient was readmitted with a lesion in the same region that was excised but that time the histopathology differed from the previous, the tumor being composed of sheets of achromic epithelioid cells, with vesicular nuclei and prominent, eosinophilic nucleoli. The tumor cells were positive for pan-cytokeratin AE1∕AE3 and negative for S100 protein, human melanoma black 45 (HMB45) and vimentin that sustained the diagnosis of basosquamous carcinoma. The paper presented an interesting case with different histopathological features from a recurrence to other, with important implication in diagnosis and prognosis. The transformation of BCC into basosquamous carcinoma sustain that the basosquamous carcinoma is better a rare, aggressive variant of BCC, than an individual lesion.