Anal canal mixed adenoneuroendocrine carcinoma in a young patient misdiagnosed as anal abscess.

Mixed neuroendocrine non-neuroendocrine neoplasms (MiNENs) are rare tumours of gastrointestinal tract, extremely rare in anal canal. We report a case of misdiagnosed MiNEN in a 38-year-old woman initially conservatively treated for a supposed anal fistula. In a second proctological evaluation, biopsy of the anal neoformation was performed and the histological specimen diagnosed a MiNEN. The complete staging showed a disseminate disease and the patient started a chemotherapy schedule. After 6 months, stable disease was revealed at the last imaging performed and radical surgery was offered to the patient that is actually on oncological follow-up without recurrence at 1 year.