What is the second most common soft-tissue tumor seen in children?
Ewing sarcoma, second to rhabdomyosarcoma.
What do you expect this tumor to look like under a slide?
This is Ewing sarcoma. Notice necrosis produced by the tumor in the diaphysis of the femur, the cells are not producing anything, just destroying and invasion of the cortex. Notice below the small, dark, round neuralectodermal cells in the slide.
What other clinical symptoms tend to go along with Ewing's sarcoma?
Fever, malaise and other systemic symptoms.
How aggressively should you treat a Ewing's sarcoma?
Aggressively with surgery, chemo and radiation. These have a high rate of metastasis to the lung and a high cure rate when treated with these methods.
Why do you see few mitoses in Ewing's sarcoma?
They are not neoplastic because they are replicating rapidly, they are neoplastic because they have decreased rate of apoptosis.
What differentiates Ewing's sarcoma from PNET?
PNETs are more differentiated than Ewing's…manifested by Homer-Wright rosettes.
Why would you check serum calcium levels and PTH levels in someone with suspected giant cell tumor?
The pathologic changes in the bone are very similar between the two conditions. Note the red-brown surface with areas of hemorrhage, cyst formation and necrosis confined to the metaphyseo-epiphyseal region
What tumor are these cells indicative of?
Giant cell tumor.
A 3 year old male with symptoms of irritability, deafness, repeated infections, hepatosplenomegaly and diffuse bone sclerosis. He also has an ulnar fracture. What enzyme deficiency causes this composition of symptoms? Why does he suffer from hepatosplenomegaly?
This is osteopetrosis. This is a disease that causes a failure to resorb bone and can present as a consequence of carbonic anhydrase deficiency. He has hepatosplenomegaly because marrow is gone and extra medullary hematopoiesis occurs in the liver and spleen.
A 15 year old boy presents with pain in the knee. X-ray shows sclerotic and lytic lesions in the metaphysis of the femur. Histological examination of cells shows cells producing collagen, fibers and osteoid. What is the most likely diagnosis of this patient?
Osteosarcoma. The tip off is osteoid producing neoplastic cells.
A 30 year old woman presents with pain and swelling around the knee joint. Bone biopsy is shown below. What enzymes are likely exhibited by the mono nucleate cells shown below?
Tartrate resistant acid phosphatase and type II carbonic anhydrase. These resorb bone and are present in hyperparathyroidism as well as giant cell tumors.
A 25 year old patient with sickle cell trait presents with a draining sinus tract. Bone biopsy is shown below. Why is this patient more susceptible to this condition? What organism is most likely causing this infection?
In sickle cell trait, they have poor vascular supply to the bones, which makes them more prone to osteomyelitis. These patients are most susceptible to salmonella infection. Note absence of osteocytes in the lacunae, indicating osteomyelitis.
Why are diabetics more prone to osteomyelitis? What organism is the most common offender in osteomyelitis in diabetics?
Peripheral neuropathy reduces sensation in the extremities and they can't feel ulcerations. Ulcerations are prone to infection. They also have decreased immunity because of decreased blood supply. They are more prone to pseudomonas infection.
What is a tip off to osteomyelitis in a child who also has a fever, chills and night sweats?
Acute swelling and tenderness.
What is the most common microbe that causes osteomyelitis?
Staph aureus. It has an affinity for collagen.
What must you test for aside from the bacteria in a patient with a draining sinus tract in chronic osteomyelitis?
Squamous cell carcinoma. Also, because chronic osteomyelitis continually signals the liver to produces acute phase proteins, including serum amyloid A, you test for amyloidosis.
Is this acute or chronic osteomyelitis?
Acute, note lots of neutrophils. Chronic osteomyelitis will show plasma cells and lymphocytes.
What serum enzyme will be elevated in this patient due to the cells indicated?
Alkaline phosphatase. This is a marker of osteoblast activity that is going on in production of this involucrum in osteomyelitis.
A 21 year old man complains of pain in his rich thigh for several months. The pain is relieved by Aspirin. His pain is worse at night and has increased gradually. How would expect this lesion to appear on radiograph?
Radiolucent with sclerotic border. This is because osteoblasts are producing osteoid, that is not mineralized, and you will see the nidus on x-ray.
Why does Aspirin help resolve pain in people with osteoid osteoma?
It inhibits COX-1, which inhibits prostaglandin production by the osteoid osteoma and decreases the patient's pain.
A 3 year old boy from an urban neighborhood presents with widening of the wrists, knees and ankles. He also has beading of the ribs and bowing of the legs. Diseases in what organs could be causing these symptoms?
Lack of vitamin D results in decreased calcium absorption in the gut. The kidney and liver are key in converting vitamin D to its active form by hydroxylating it.
How is Rickets different from osteomalacia?
In kids, bone grows at the epiphysis. When they are lacking in calcium, epiphyseal bone growth is disregulated, and you get an overgrowth of bone matrix and cartilage, causing bone deformities (top image). In adults, bone grows appositionally. This results in fractures because of weak bone due to decrease in bone mineralization (bottom image).
What drives secondary hyperparathyroidism?
Hypocalcemia. The parathyroid continually secretes PTH, which causes bone resorption. The kidney can also cause it because phosphate is retained and increases bone resorption.