The morphological examination of strumal carcinoid showed struma ovarii with a thyroid follicle-like structure [positive for thyroid transcription factor 1 (TTF1), thyroglobulin, CD56, cytokeratin (CK) 19, and negative for Hector Battifora and mesothelioma 1 (HBME1)], and a neuroendocrine cell component with a trabecular arrangement and island growth (positive for synaptophysin, chromogranin, CD56, and CK7 negative), which were interlocked and intimately associated.