Sarcoid: Body and MSK Radiology
Review of body and MSK findings of sarcoidosis for the ABR core exam. Study hard and prepare to succeed!
Show Notes/Study Guide:
Abdominal and pelvic sarcoidosis:
True/False? Sarcoidosis can involve any abdominal organ.
True. Based on my best guess they may be most likely to show you liver lesions because these are often well-depicted on imaging. If you see a liver lesion (or any solid organ abdominal lesion and/or peritoneal lesion) and a mediastinal/hilar lymphadenopathy sarcoid needs to be included in your differential diagnosis for the board exam question. Isolated solid organ abdominal disease without thoracic manifestations of sarcoid is rare.
True/False? Sarcoidosis can cause cirrhosis and portal hypertension.
True, in setting of chronic liver sarcoidosis. If you are ever encountered with a question asking whether sarcoidosis can do basically anything the answer is yes for board exams.
If sarcoidosis involves abdominal solid organs what is the most common imaging manifestation?
Sarcoid granulomas will most commonly manifest as numerous small mas-like nodules/masses. These may coalesce and you may see larger nodules on a background of numerous smaller nodules. You can also see diffuse organ enlargement to include hepatomegaly and splenomegaly with a heterogeneous parenchymal pattern with or without discrete nodules.
What other entities can present similarly to sarcoidosis in the abdomen and pelvis?
Lymphoma, metastatic disease, mycobacterial and fungal infections.
Sarcoid for the ABR Core Exam. Matt Covington, MD
Gastric sarcoid can present with the appearance of linitis plastica. What is linitis plastica and what other disease processes can cause this appearance?
Linitis plastica of the stomach typically results from diffuse gastric adenocarcinoma involving the submucosal stomach causing diffuse thickening of the gastric wall. Differential considerations include metastatic disease, lymphoma, granulomatous disease to include Crohn’s disease and gastric amyloidosis and sarcoidosis. On a barium fluoro study you see inability of the stomach to distend and loss of the gastric mucosal folds. On CT you will see diffuse gastric wall thickening with possible perigastric lymphadenopathy.
Sarcoidosis of the kidney can result in what laboratory abnormalities on blood and urine analysis?
Renal sarcoidosis can cause hypercalcemia and hypercalciuria along with renal calculi. The physiology is complex and likely beyond the scope of the ABR Core Exam. In severe cases, renal failure can result from severe granulomatous nephritis.
Can sarcoidosis affect the testes?
Yes. Sarcoid can involve the testes and epididymis and may manifest as hypoechoic lesions. Differential considerations again include lymphoma, metastatic disease, and other granulomatous diseases.
Note that sarcoidosis can also cause abdominal and pelvic lymphadenopathy (FDG avid) as well as peritoneal nodularity and even ascites formation. Biopsy is necessary with these findings to confirm sarcoidosis and exclude malignancy.
Sarcoidosis is one potential cause of medullary nephrocalcinosis. What are other potential causes of medullary calcinosis?
A mnemonic for medullary calcinosis that is commonly out there is “HAM HOP”:
H: hyperparathyroidism
A: acidosis (renal tubular acidosis)
M: Medullary sponge kidney
H: Hypercalcemia/hypercalciuria (sarcoid and milk-alkali syndrome)
O: oxalosis
P: Papillary necrosis
Sarcoid for the ABR Core Exam. Matt Covington, MD
Note that medullary calcinosis is way more common than cortical nephrocalcinosis. Causes of cortical nephrocalcinosis are broad but include renal ischemic injury, renal transplant rejection, infection, chronic glomerulonephritis, nephrotoxic drug injury, Alport syndrome, many other causes. Also note that calcinosis of the renal pyramids has its own differential diagnosis to include renal tuberculosis, sickle cell disease, Lasix over-use, renal papillary necrosis, hyperuricemia which has its own broad differential diagnosis.
Musculoskeletal sarcoid:
What are common MSK findings of sarcoid?
Sarcoid can involve any bone but the small bones of the hands and feet are more commonly affected. On board exams, pay attention for sarcoid to be shown as lucencies in the mid and distal phalanges of the 2nd/3rd digits of the hand, enchondroma-like lesions with a lytic lacelike pattern. You can see soft tissue thickening of the fingers as well “sausage digits”.
Sarcoid can present with multiple lytic lesions. What are other differential considerations for multiple lytic lesions?
A mnemonic for multiple lytic lesions that is commonly out there is POEMS:
P: Paget’s or hyperparathyroidism
O: Osteomyelitis
E: eosinophilic granuloma
M: metastases (think thyroid, renal primaries), Multiple myeloma
S: Sarcoid
POEMS is not all inclusive, but it does remind you of many common entities and is an actual word which for me helps me to actual remember it unlike other mnemonics that exist such as “FEEMHI”. You can look that one up on your own, if interested.
What is a potential complication of lytic sarcoid lesions in the bones?
Pathologic fractures can occur due to the bony osteolysis. These may not heal well so you may see chronic bone collapse and poor bony alignment following pathologic fractures.
Sarcoid for the ABR Core Exam. Matt Covington, MD
What are differential considerations for a sausage digit?
First, I would think of psoriatic arthritis with sausage digits (think of this first before sarcoid or other causes). Other potential causes include sarcoid, sickle cell anemia, TB, gout, osteomyelitis among other etiologies.
Can sarcoid cause arthritis?
As I said before, sarcoid can do just about anything so the answer is yes. Sarcoid arthritis is most common in women <40 years. This will typically affect multiple joints and may present with joint pain, swelling, and erythema. Sarcoid arthritis usually resolves on its own within 6 months of onset, but chronic sarcoid arthritis can occur but is rare.
What is Lofgren syndrome?
Lofgren syndrome is a form of acute systemic sarcoidosis manifesting with polyarthritis, erythema nodosum (painful nodular red rash, most commonly on the shins), fevers and bilateral hilar adenopathy. Don’t confuse this with Loffler syndrome which is pulmonary eosinophilia. Lofgren syndrome is most common in women <40 years. Polyarthritis is often symmetric and most commonly manifests in the ankles but can affect any joints. Lofgren syndrome is so specific for sarcoid that you may not need to biopsy to confirm the disease if you have this spectrum of symptoms. Take note that Lofgren syndrome
is one of the ONLY specific manifestations of sarcoidosis.
What are differential considerations for erythema nodosum?
Many but common considerations include post-infectious state (strep common), TB, sarcoid, IBD, pregnancy, drug reaction, or paraneoplastic manifestation of leukemia/lymphoma.
Can sarcoid affect the muscles?
Yes, you can see single or multifocal muscular sarcoidosis. Look for soft-tissue masses versus diffuse infiltrative lesions in the muscles, most common in lower extremities due to granulomatous muscular infiltration.
for the ABR Core Exam. Matt Covington, MD
What are cutaneous manifestations of sarcoidosis?
Broad spectrum of manifestations that include nodules, plaques, papules, etc. Those specifics are unlikely to be tested on radiology board exams. However, remember erythema nodosum can be seen with sarcoidosis along with other entities, as above. You can have lupus-like rashes around the eyes/nasolabial folds with sarcoidosis.
General sarcoidosis considerations:
What are common therapies to be aware of for sarcoidosis?
For mild manifestations no therapy may be given. Steroid treatment is the main therapy for most cases. More severe cases may use various immune modulating drugs and end-stage sarcoid may require organ transplantation.
Do we monitor sarcoid patients with imaging? If so, how?
As of this episode and to my knowledge there are no definite guidelines for monitoring sarcoid patients with imaging, but many patients will have a chest radiograph every 6 months or so along with clinical follow-up/monitoring to check PFTs, renal function, calcium levels, EKG. etc.
