27

CASE 27


A 42-year-old man presented to his primary care provider with complaints of headache, sweating (diaphoresis), and a sense of his heart pounding in his chest (palpitation). He stated that these attacks would begin suddenly (paroxysmal symptoms) and subside gradually. The attacks would last for perhaps 10 minutes and occur about two to three times per week. An initial arterial pressure measurement was normal, 124/82. Ten minutes after this initial recording, the patient complained that he was experiencing an abrupt onset of headache, sweating, and palpitation. Another arterial pressure measurement was obtained, which was recorded as 165/94. Laboratory findings indicated that the patient had a pheochromocytoma, a neoplasm of chromaffin cells.



WHAT GERM LAYER GIVES RISE TO CHROMAFFIN CELLS?


The cortex and medulla of the adrenal gland have separate origins. The mesothelium (derived from mesoderm) lining the posterior abdominal wall differentiates into the cortex, and the medulla forms from neural crest cells, which are derived from neuroectoderm.



WHERE ARE CHROMAFFIN CELLS FOUND IN THE HUMAN BODY?


Although chromaffin cells are chiefly located in the adrenal medullae, they are also widely distributed extra-adrenally. Some of these extra-adrenal sites of chromaffin (Fig. 3-46) cells are:


• Organ of Zuckerkandl. This aggregation of chromaffin cells is located near the bifurcation of the aorta.

• Along the paravertebral ganglia of the sympathetic trunk.

• Carotid bodies

• Urogenital system. Chromaffin cells may be located along the kidneys, ureters, epididymis, prostate, and ovary.

image

FIGURE 3-46 Locations of chromaffin tissue as quantitated by the presence of pheochromocytomas. Numbers based on 100 patients.


(Towsend C et al.: Sabiston Textbook of Surgery, 17e. WB Saunders, 2004. Fig. 37-22. From Manger WM, Gifford RW, Melicow MM: Pheochromocytoma. New York, Springer-Verlag, 1977, p. 45.)


These extra-adrenal sites are clinically important as 10% of pheochromocytomas occur here.



ONE OF THE LABORATORY FINDINGS IN THIS PATIENT WAS ELEVATED PLASMA CHROMOGRANIN A. WHAT IS THE ROLE OF CHROMOGRANIN A AND WHY WOULD IT BE ELEVATED IN A PATIENT WITH A PHEOCHROMOCYTOMA?


Chromogranin A is one of a family of chromogranin proteins. These proteins are synthesized by the chromaffin cells and packaged by the Golgi complex, along with catecholamines, into secretory vesicles. It is believed that chromogranins serve as binding proteins for catecholamines. Consequently, chromogranins and catecholamines would be elevated in a patient with a pheochromocytoma. Chromogranins (A and B) also are secreted in nonfunctional pancreatic endocrine tumors.

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Jun 16, 2016 | Posted by in ANATOMY | Comments Off on 27

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