Why does renal failure cause hyperparathyroidism?
Q. Can you explain why patients with renal failure have hyperparathyroidism?
A. Yes – but first, a quick note about the parathyroid. (more…)
Q. Can you explain why patients with renal failure have hyperparathyroidism?
A. Yes – but first, a quick note about the parathyroid. (more…)
Q. How can basal cell carcinoma be considered both malignant and invasive if it never metastasizes? (more…)
Q. I have a question about H. pylori. I understand that it’s mainly the host’s inflammatory response to the H. pylori‘s presence at the epithelial cell surface that causes the ulcers.  (more…)
I’m putting the final touches on a new study guide!
This one is a complete hematopathology guide that covers everything you need to know for medical (and dental) boards. (more…)
From time to time, I get questions regarding the connection between hypersensitivity reactions and autoimmune diseases. (more…)
Q. I am wondering if you wouldn’t mind clarifying something for me about which bacteria are actually the ones that will cause BLOODY diarrhea vs watery diarrhea. (more…)
Q. I was wondering if you could help clarify two coagulation tests. (more…)
Q. What is the difference between a neurofibroma and a neuroma?
A. A neuroma is a general term that applies to any of a number of different things (neoplastic or non-neoplastic) that make a nerve or nerve bundle swell. Usually, another word is attached to give more specific meaning.
Neoplastic neuromas are tumors of any part of a nerve (including the surrounding myelin); sometimes the term is used more broadly to refer to any tumor of neural tissue. An example of a neoplastic neuroma is acoustic neuroma, a benign tumor surrounding the 8th cranial nerve (you can also call this tumor a schwannoma, since it is a neoplasm derived from the Schwann cells surrounding the nerve, not the nerve itself).
The main non-neoplastic neuromas are traumatic neuroma (a non-neoplastic reaction of a nerve to some sort of damage) and Morton’s neuroma (which is not even a neuroma, but just an accumulation of fibrous tissue around a nerve, usually in the foot).
Neurofibromas are benign neoplasms derived from the myelin sheath of peripheral nerves (just as a reminder: the myelin surrounding peripheral nerves is supplied by Schwann cells; the myelin surrounding central nerves is supplied by oligodendrocytes). They often occur in the context of neurofibromatosis, a hereditary condition characterized by multiple cutaneous neurofibromas, pigmented skin lesions, skeletal abnormalities, macrocephaly, epilepsy, and a bunch of other findings. In the photo above, the patient has multiple neurofibromas scattered over his entire body.
Neurofibromas are like schwannomas, in that they are derived from schwann cells. However, a schwannoma has mostly just schwann cells in it, whereas a neurofibroma has a bunch of other cell types, like fibroblasts, endothelial cells, and mast cells.
Q. Why does PV, plasma volume, rise in polycythemia vera? This seems counterintuitive. (more…)
Q. I was reading over some of your blog posts (which are awesome) and I came across the one where you stated that “Essential thrombocythemia is not considered a cause of disseminated intravascular coagulation.” (more…)
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