title: Unusual gastric mucosal infiltration by a medullary thyroid carcinoma: a case report.
abstract: BACKGROUND
  Medullary thyroid carcinoma accounts for approximately 1 to 2 % of all thyroid carcinoma cases. The most common route of dissemination is to locoregional lymph nodes. Distant metastases commonly affect bones, lungs, and liver. We present a case of a white woman with a 25-year history of medullary thyroid carcinoma on multiple medications including tyrosine kinase inhibitor therapy for the last 11 months, who exhibited unusual diffuse infiltration of advanced stage medullary thyroid carcinoma to her gastric mucosa.
  
  
  METHODS
  A 53-year-old white woman presented with increasing fatigue, loss of appetite, and severe epigastric pain radiating to her back. She had a history of medullary thyroid carcinoma (pT2pN1b), diagnosed 25 years ago and treated by complete thyroidectomy and repeated bilateral cervical lymph node dissection. Medical therapy included octreotide 20 mg every 4 weeks, which was switched to the tyrosine kinase inhibitor vandetanib 300 mg/day 11 months ago when computed tomography scanning revealed progressive mediastinal lymph node and diffuse and symptomatic pulmonary metastases. Of note, she demonstrated macroscopically stable pulmonary and mediastinal lymph node metastases; however, her calcitonin serum levels dramatically increased. Computed tomography scanning revealed a single new intrahepatic lesion (4 mm) as well as multiple (>10) new supraclavicular lesions suggestive of medullary thyroid carcinoma progress. As proven by gastric biopsy and immunohistochemical evaluation, her epigastric pain was explained by a diffuse infiltration of her gastric mucosa by metastatic medullary thyroid carcinoma. Subsequently, she rapidly deteriorated and died.
  
  
  CONCLUSIONS
  The current case report shows for the first time an unusual metastatic infiltration of the gastric mucosa by medullary thyroid carcinoma. When treating these patients, it is important to include this differential diagnosis during follow-up.
authors.affiliation: Department of Internal Medicine III, Giessen University Hospital, Klinikstrasse 33, 35392, Gießen, Germany. thomas.karrasch@innere.med.uni-giessen.de.
authors.forename: T
authors.identifier: http://orcid.org/0000-0001-6850-588X
authors.initials: T
authors.lastname: Karrasch
authors.affiliation: Central Interdisciplinary Endoscopy Unit (ZIVE), Giessen University Hospital, 35392 Gießen, Germany.
authors.forename: W
authors.initials: W
authors.lastname: Doppl
authors.affiliation: Department of Radiology, Giessen University Hospital, 35392 Gießen, Germany.
authors.forename: F C
authors.initials: FC
authors.lastname: Roller
authors.affiliation: Department of Internal Medicine III, Giessen University Hospital, Klinikstrasse 33, 35392, Gießen, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Schäffler
authors.affiliation: Department of Pathology, Giessen University Hospital, 35392 Gießen, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Schäffer
authors.affiliation: Department of Pathology, Giessen University Hospital, 35392 Gießen, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Gattenlöhner
mesh_terms: D018278:Carcinoma, Neuroendocrine / Q000175:diagnosis* / Q000473:pathology*; D017809:Fatal Outcome; D005260:Female; D005753:Gastric Mucosa / Q000473:pathology*; D006801:Humans; D008875:Middle Aged; D016609:Neoplasms, Second Primary / Q000175:diagnosis*; D013274:Stomach Neoplasms / Q000175:diagnosis* / Q000556:secondary*; D013964:Thyroid Neoplasms / Q000175:diagnosis* / Q000473:pathology*
keywords: Case report; Distant metastasis; Epigastric pain; Gastric mucosa; Medullary thyroid carcinoma; Tyrosine kinase inhibitors