Question

A 72-year-old man, who is known to have adenocarcinoma of lung, s/p left upper lobe wedge resection and chemoradiation presents with left flank pain, dysuria, and difficulty voiding. Urine examination shows moderate RBCs. Renal ultrasound is unremarkable. The patient has a history of chronic DVT and is currently on enoxaparin (low molecular weight heparin). You have been consulted for a low platelet count (29,000/mcL). His other pertinent laboratory tests include LDH- 570; heparin-induced antibody tested negative, PT/aPTT 15.7 and 35.1 in addition to those listed below.

Hb count 8.1 gm/dl
PT 15.1 (10.5-14.0)
PT mix 12.8 (corrected)
aPTT 54.7 (22-34.0)
aPTT mix 29.9 (corrected)
Thrombin time 20.2 (16.0-23.0)
Fibrin degradation products 320 (0.0-2.5)
Fibrinogen 102 (150-350)
D-dimer 64.0 (0.0-0.4)
AT-III 103% (80-120%)
Schistocytes- Occasional
Platelet count- 29,000/mcL (decreased)
Bilirubin 1.2 mg/dl
Cr 1.5 mg/dl

What is the diagnosis?

Answer 1

The diagnosis is likely disseminated intravascular coagulation (DIC), as the lab findings and clinical picture, including thrombocytopenia and markedly elevated d-dimer and fibrin degradation products, match the criteria for DIC. There is no evidence of heparin-induced thrombocytopenia (HIT) given the negative heparin-induced antibody test.

Step-by-step explanation:

The patient's presentation and laboratory findings, such as low platelet count (thrombocytopenia), raised LDH, presence of schistocytes, elevated d-dimer and fibrin degradation products, along with borderline prolonged PT/aPTT and reduced fibrinogen levels, are suggestive of disseminated intravascular coagulation (DIC). The negative heparin-induced antibody test rules out heparin-induced thrombocytopenia (HIT). Given the clinical history of adenocarcinoma, the patient likely has a paraneoplastic syndrome causing the DIC, which is exacerbated by the underlying malignancy.

Considering the flank pain, dysuria, and difficulty voiding, there may be an associated urinary tract involvement; however, with an unremarkable renal ultrasound, this does not explain the thrombocytopenia and other lab findings suggestive of DIC.