Highly proliferative anal neuroendocrine carcinoma : molecular and clinical features of a rare, recurrent case in complete remission

• Background Poorly differentiated anal neuroendocrine carcinomas (ANECs) are rare lesions with poor prognosis, and the molecular etiology is only partially understood. Case presentation At our institution, we have treated and followed a patient with such a rare ANEC. He had primarily surgery followed by three rounds of repeated surgery for loco-regional recurrences. He also received three different combinations of chemotherapy and external beam radiation. At last follow-up 13 years since the primary diagnosis, the patient had been in complete remission for nine years. The patient's medical files were re-examined, including laboratory, radiology and clinical examinations. Histopathology was re-assessed, and expanded immunohistochemistry was performed from tissue specimens from the four surgical procedures. In addition, the molecular genetic status was evaluated through next-generation sequencing. The initial tumor was consistent with a 59 mm small cell neuroendocrine cancer with a Ki-67 index of 80%. Regional lymph node metastases were evident, and immunohistochemistry supported a neuroendocrine origin. A PCR screening detected human papilloma virus type 45 DNA (high-risk subtype), and focused next-generation sequencing found a missense mutation in thePhosphatidylinositol-4,5-Bisphosphate 3-Kinase Catalytic Subunit Alpha(PIK3CA) gene. In tissues representing subsequent recurrences, the Chromogranin A expression was lost, and the Ki-67 index increased to 90%. Conclusions For the first time, we report the detection of HPV45 in a case of ANEC. To our belief,PIK3CAmutations have also not been previously demonstrated in this tumor entity. In highly malignant ANECs, cure can in rare cases be achieved. Although speculative, expression of HPV45 and/or thePIK3CAmutation may have contributed to the favorable outcome.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Cancer och onkologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Cancer and Oncology (hsv//eng)

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Gastroenterologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Gastroenterology and Hepatology (hsv//eng)

Nyckelord

Anal neuroendocrine carcinoma

Remission

HPV

PIK3CA

Mutation

Case report

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