Case Presentation:

A 55–year–old woman presented to Emergency Department (ED) complaining of two weeks history of progressive shortness of breath, lethargy and decreased appetite. She was diagnosed with small cell lung cancer 5 months ago which was treated with chemotherapy and radiation. Last treatment with chemotherapy was 4 weeks prior to this illness. Other medical problems related to her malignancy included chronic back pain, syndrome of inappropriate antidiuretic hormone hypersecretion (SIADH), Superior vena cava syndrome and metatastatic disease to brain. Current medications were omeprazole, dexamethasone and demeclocycline. She had a 40–pack year history of smoking but denied alcohol or illicit drug use. On admission she was afebrile, her vitals were stable except respiratory rate of 22. She was receiving 2 L/min of oxygen using a nasal cannula with pulse oxygen saturation of 99%. Physical examination was remarkable for hepatomegaly and bilateral lower extremity edema. Her laboratory studies showed the following: serum sodium 135 meq/L, potassium 4.5 meq/L, chloride 93 meq/L, bicarbonate 18 meq/L, blood urea nitrogen (BUN) 73 mg/dL, creatinine 2.13 mg/dL , and anion gap 24. Her complete blood count showed anemia (hemoglobin 7.9 g/dL), thrombocytopenia (26 TH/mL) and white blood cells 11.3 TH/mL. Venous lactic acid level was 7.5 mmol/L which was followed by arterial blood analysis that was consistent with pH 7.34, PA CO2 28mm/Hg, PA O2 113mm/Hg, HCO3 15.1mmol/L and lactic 11.3 mmol/L. A noncontrast enhanced computed tomography of the abdomen and pelvis showed hepatomegaly and innumerable hepatic hypodensities compatible with metastatic disease to the liver. Patient was started on intravenous normal saline along with empiric antibiotics and admitted to medical service. On hospital day 2, patient became lethargic and venous lactic acid levels increased to 18.1 mmol/L. According to patient and her family’s wishes a palliative care consult was initiated. Patient died less than 48 h after admission.

Discussion:

Lactic acidosis is a form of metabolic acidosis associated with accumulation of lactate in blood stream. It is most commonly associated with conditions that cause decreased tissue perfusion. Another form of lactic acidosis referred as Type–B Lactic acidosis occurs in normoxic and stable perfusion states. This form of lactic acidosis is most commonly seen in hematological malignancies but can rarely be seen in solid tumors like lung cancers. Based on literature search we found 9 similar cases associated with lung cancer and all patients died between 2 days to 16 weeks as also witnessed in this case. This form of lactic acidosis should be considered as a marker of aggressive tumor activity and pending mortality.

Conclusions:

Type–B lactic acidosis is a form of metabolic acidosis that can occur as a consequence of aggressive solid tumor activity and should be viewed as a marker of poor prognosis.