In February 2000, a 32 year old man came to the hospital emergency department for pain in the left shoulder and lumbar spine. Routine physical examination and laboratory tests were irrelevant. The radiological study showed generalised lytic bone lesions. Abdominal thoracic CT scan showed no images suggestive of visceral neoplasia. Gastroscopy, barium enema, abdominal, testicular and prostate ultrasound were normal. In order to establish a diagnosis, a bone marrow biopsy was taken from the iliac crest. Microscopically, the bone marrow showed a partial replacement of its usual cellularity by a neoplasm consisting of epithelial nests in a fibrous stroma in some areas, while in other areas these nests are surrounded by the usual bone marrow cellularity and are made up of polygonal cells with rounded or oval nuclei, with a soft appearance without prominent nucleoli and very few mitoses. The immunohistochemical study showed negativity for oestrogen receptors, S-100 protein, HMB45, p53, bc1-2 and synaptophysin. Positivity in 25% of the nuclei with MIB-1 and in 90% of the nuclei with p27 and diffuse and strong positivity to progesterone receptors, chromogranin A, neuronal specific enolase, carcinoembryonic antigen and in less than 50% of the cells to calcitonin, amyloid was not detected with Congo Red staining. With these elements, a diagnosis compatible with bone metastasis of medullary thyroid carcinoma was made. Serum calcitonin levels were 3,500 pg/ml (normal 15-100) and CEA 231 ng/ml (normal 0.01-5), with serum levels of Ca 125, Ca 19.9 and PSA being normal.

Given the poor physical condition of the patient, he was sent to the oncology department of our reference hospital in Jaén, where a small solid thyroid nodule with calcium was found ultrasonographically in the left lobe, which was not removed. After investigating the family, no history of thyroid pathology was found.
A first line of chemotherapy (CDDP-ADR-VP16) was administered for 6 months, with no response. Palliative radiotherapy was also given to the dorsal lumbar spine. At the beginning of February 2001, a second line of chemotherapy (CTX-DTIC) was started, which was suspended a few days later due to the patient's poor condition, progression of bone metastases and the appearance of pulmonary metastases. The patient died on 21 February 2001. The family did not authorise the autopsy.