A 14-year-old girl was found to have a large, non-tender breast mass with anemia and thrombocytopenia. The diagnosis of an undifferentiated carcinoma of unknown primary was made after open breast biopsy of the mass with negative immunohistochemical studies for breast malignancies.

Further evaluation showed extensive metastatic disease affecting the bone marrow, ribs, liver, and brain with magnetic resonance imaging evidence of carcinomatous meningitis.

Despite 2 months of chemotherapy and intensive supportive care, the patient died of severe lactic acidosis and disseminated intravascular coagulation after exaggerated menstrual bleeding. The association of severe lactic acidosis and undifferentiated carcinoma of unknown primary in an adolescent has not been previously described.

Cheng JC, Esparza SD, Knez VM, Sakamoto KM, Moore TB. (2004) Severe lactic acidosis in a 14-year-old female with metastatic undifferentiated carcinoma of unknown primary. J Pediatr Hematol Oncol. 2004 Nov;26(11):780-2. Division of Pediatric Hematology-Oncology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.