Diagnosis: Adenocarcinoma with atrophic features.     

            Comment: The clue for the diagnosis of adenocarcinoma is presence of usual neoplastic acini as seen in Fig. 5, otherwise the diagnosis is extremely difficult. The main differential diagnosis is partial atrophy. Immunohistochemistry may be misleading because in partial atrophy there is spacing of basal cells and the acini may be negative for high-molecular cytokeratins. In this particular case usual adenocarcinoma was also present in other sections of the biopsy.