Case Of the Month 8 – Answer

This patient presents with many different and varying complaints, but the most telling is the nonpalpable purpura. Purpura can be divided into non-palpable (macular) and palpable. “Non-palpable” can be further described as petechiae (small, usually <3mm) vs. purpura (3mm-1cm) vs. ecchymosis (large, >1cm). None of these forms will blanch when pressed. Purpura may result from any of three abnormalities in hemostasis – platelets, plasma coagulation factors, or blood vessel structure.

Our patient has non-palpable purpura which can be caused by thrombocytopenia (such as TTP and many other conditions), conditions that produce high intravascular pressures (vomiting, coughing, seizures, etc.), external trauma, sepsis/DIC, changes in coagulation factors, active anticoagulants, skin fragility (such as collagen diseases), deficiency of vitamin K or C, and a multitude of drugs. After trauma, infection, and/or drugs have been eliminated, the key in teasing out a cause for purpura starts with identifying whether thrombocytopenia is present. Using further labs tests will then help categorize the differential diagnosis. The following algorithm was taken from a pediatric emergency medicine textbook but is applicable to adult patients as well:

Following this algorithm using the data we have and incorporating the associated symptoms and findings of this patient allows us to arrive at our most likely diagnosis.

This man has vitamin C deficiency, otherwise known as scurvy. Vitamin C plays a key role in the triple-helix formation of collagen and thus, a deficiency produces impaired collagen. This impaired collagen can be found in skin and capillary blood vessels and is much weaker than normal collagen; this allows for easier tearing of tissues and vessels and leads to the classical purpura of scurvy. It is also found in dentine which leads to bleeding gingivitis and loss of teeth and osteoid which is used for bone formation by osteoblasts. This, in turn, results in osteoporosis and subperiosteal hemorrhage. Vitamin C plays an important role in many other body systems and can cause the “classical” 4 H’s of scurvy: hemorrhage, hematologic abnormalities, hyperkeratosis, and hypochondriasis. Note that the more common initial presentation of scurvy includes nonspecific symptoms such as diarrhea, malaise, poor appetite, fever, and a cranky demeanor.

Treatment of scurvy involves replenishment of vitamin C stores. Stores are restored fairly rapidly with symptom improvement within two days and complete cure by 1 week. There are two treatment regimens:

1. 100mg 3-5 times per day until 4g is consumed, and then decreasing the dosing to 100mg daily until 1 week in total is completed
2. 1g daily for 2-3 days followed by 500mg daily for 1 week.

Neither regimen appears to be more beneficial than the other. Upon completion of  treatment, the patient must be informed of the dietary changes required to sustain a normal level of vitamin C.

So in summary, purport that is not explained by obvious trauma or external forces must be explored and using the above algorithm will help guide the differential diagnoses. In particular, non-thrombocytopenic purpura with no evidence of coagulopathy will point to an abnormality in blood vessel walls. If bloodwork is all normal, suspicion should be raised that a patient’s vascular structure has been compromised.

References:

Pimental L. Scurvy: historical review and current diagnostic approach. Am J Emerg Med. 2003 Jul;21(4):328-32.

Cohen AR. Rash–purpura. In: Fleisher GA, Ludwig S, et al., eds. Textbook of pediatric emergency medicine. 3d ed. Baltimore: Williams & Wilkins, 1993: 430-8

Scurvy. http://emedicine.medscape.com/article/125350-overview