In "Nate's method"... what is the diagnosis?

Nate Hellman, the founder of this blog, was a personal friend. We trained together as MGH Renal Fellows. It has been three years since his passing. I often wonder how much he would have achieved by now. For sure, he would be on staff at Mass General and on faculty at Harvard Medical School. He would be well immersed in setting up his independent research career. He would be the caring doctor we all knew him to be. And most certainly, he would be writing this blog.

Those of us who knew him personally, know that Nate had the ability to write and release his brilliant thoughts to the world with little worry or inhibition, one of many traits I always admired in him. I think it came from his wonderful ability to laugh at himself and remain honest and real, no matter what. I have decided to start blogging, in an effort to remind myself, all of us here at MGH and all of you out there of “Nate’s method.” At least, I intend to try…

Here is the unknown case that was presented to me at the MGH Renal Grand Rounds this past Tuesday. One of our Renal Fellows, Dr. Jie Cui, presented the case, and will be blogging on her own thoughts on PAN soon (I have inside information here!):

HPI:

41 yo M with no PMH was admitted with acute onset pain radiating to his R groin, 10/10, sharp and persistent. In the ER, he was found to have BP 188/116, mildly elevated Cr to 1.3, and elevated LDH 520. His CT showed bilateral renal infarcts and renal artery clot.

Home Medication: None

Physical Exam:

Vital Signs: T 98 HR 76 BP 120/90

GEN: Well appearing man in NAD

HEENT: MMM, oropharynx clear; PERRL.

Cards: NSR, RRR, normal S1, S2, no murmur/gallops/rubs

Chest: CTA B/L, no wheezing/rales/rhonchi

Abd: Soft/ND, + BS, RLQ (+) tenderness, no rebound/guarding, no bruits

Back: no CVA tenderness

Ext: normal tone, no edema, 5/5 muscle strength, no joint tenderness or deformities

Skin: no rash

Results:

NA 135, K 3.7, CL 101, CO2 23, BUN 10, CRE 1.42, EGFR 55, GLU 80
CA 8.8, MG 2.3, TBILI 0.5, TP 6.9, ALB 3.5, GLOB 3.4, LDH 363 CRP 11.8
ALT/SGPT 18, AST/SGOT 12, ALKP 73, TBILI 0.5
FE 33, TIBC 194, TIBC 161
WBC 9.84, RBC 3.98, HGB 12.7, HCT 36.1, MCV 90.7, MCH 31.9, MCHC 35.2, PLT 226
PT 14.5, PT-INR 1.1, PTT 59.0,

Hypercoagulable work up (-) antiphospholipid antibodies (-), homocysteine (-)
ANA (-), ANCA (-), C3, C4 normal, Cryo (-),hepatitis (-), HIV (-),

Urine protein/cr: 0.12, 24 hour urine creatinine clearance: 54ml/min

Urine sediment: 1-2 WBC, 1-2 normal RBCs, no casts.

All Cultures were negative.

CT abdomen and pelvis:

1. Bilateral renal artery clot

2. There is a focal, geographic area of decreased perfusion involving the upper pole of the right kidney.

3. A focal area of cortical volume loss and decreased enhancement in the left kidney is also noted, suggestive of scarring.

Questions for the discussant:

1. What is the differential diagnosis?

2. What diagnostic procedure would you perform?

We discussed the following differential:

The differential of acute flank pain is:

Renal calculus – but no evidence on CT

Pyelonephritis – but cultures were negative

Other abdominal pathology as source of the pain – pancreatitis, cholecystitis – but no evidence on CT

Renal Infarct – yes, there is evidence for this on CT

This brings us to the differential for renal infarct:

Thromboembolic – from heart or aorta – but echocardiogram, including transesophageal echo with bubble study were negative, also cultures remained negative at all times

In situ thrombosis – no clear evidence for this

Renal artery occlusion from aortic dissection – no evidence for this on CT

Spontaneous or iatrogenic renal artery dissection – no evidence for this on CT

Fibromuscular dysplasia – no evidence for this based on history (no h/o HTN for example)

Segmental arterial mediolysis – possible, but again not supported by the CT

Complication of anti-phospholopid syndrome – but entire hypercoagulability panel was negative

Cocaine use – this could easily be the cause of this bilateral renal artery thrombosis, the patient continued to deny cocaine use, but this was strongly suspected, urine tox studies were apparently negative, but timing may have been the issue there...

Polyarteritis nodosa – interesting and also likely, the patient is HBV negative, but could be “idiopathic” PAN.

Given the above differential, a renal angiogram was performed which was read as consistent with medium vessel vasculitis, suggestive of PAN.

The patient was treated with steroids and cytoxan and is presently doing well, with creatinine stable in the 1.4 range and no new symptoms.

Still, we were left a bit dissatisfied with this outcome, as the diagnosis of PAN is not consistent with bilateral renal artery clot, which was clearly seen on CT in this patient.

I am still worried about cocaine use or another etiology…

Please comment and let us know your thoughts!