BLEEDING UNDER THE SKIN

Conditions of the skin, subcutaneous tissue, vascular wall, and blood may all be associated with bleeding under the skin or purpura, thus both anatomy and physiology must be used to develop this differential (Table 12). The skin may hemorrhage from infections such as smallpox, scabies, chickenpox, and measles, especially when the patient traumatizes the area to relieve the itching. A bug bite also may cause hemorrhage by this means. Focal and metastatic neoplasms may cause hemorrhage in the skin, whereas degeneration of the skin may lead to senile purpura. Trauma is by far the most common cause of hemorrhage of the skin.

BLEEDING UNDER THE SKIN

The subcutaneous tissue is distinguished separately, so that one will recall the Ehlers–Danlos syndrome and pseudoxanthoma elasticum. The vascular wall may be damaged by numerous etiologies. The most important infectious etiologies are subacute bacterial endocarditis and meningococcemia, but typhoid fever, Weil disease, and Rocky Mountain spotted fever should not be forgotten. Systemic neoplasms that infiltrate the vascular wall (such as leukemia) are significant causes, but these usually cause purpura by inducing thrombocytopenia. Vascular degeneration and deficiency diseases such as scurvy are uncommon causes of purpura. Toxic conditions are more likely to be related to bone marrow suppression of platelets. Congenital lesions such as hereditary telangiectasias are important to remember.

Most important of all are the allergic and autoimmune disorders because something can be done to alleviate the condition (e.g., steroids or immunosuppressants). Henoch–Schönlein purpura is a significant form of allergic vasculitis, but periarteritis nodosa is important as well. Trauma is just as important here as in the skin. Thus, a ruptured varicose vein, crush injury, whooping cough, or contusions are important causes of purpura. Endocrine disorders also cause vascular purpura (as in Cushing syndrome).

Disorders of the blood figure prominently in purpura. Significant among these are the numerous disorders that cause suppression or increased destruction of platelets. Toxic disorders such as gold injections, salicylate ingestion, potassium iodide, quinidine, ergot, and chloral hydrate are just a few of these. It is best to assume that any drug may cause purpura until proven otherwise. Leukemic overgrowth of the bone marrow may cause purpura because of thrombocytopenia, but any neoplasm that infiltrates the marrow (myelophthisic anemia) must be considered. Autoimmune disease suggests the purpura of idiopathic thrombocytopenic purpura (ITP) and lupus erythematosus.

Degenerative disorders bring to mind aplastic anemia, although this is often caused by drug suppression of the bone marrow. Congenital disorders are more often the cause of coagulation disorders such as hemophilia, but coagulation disorders are often associated with heparin and dicoumarin therapy as well. Trauma and endocrine disorders do not figure as prominently here. There may still be a platelet disorder even though the platelet count is normal. Thus, one should investigate for hereditary thrombasthenia and salicylate toxicity, among other things, by doing a clot retraction test as a screen.

Approach to the Diagnosis

The clinical approach to purpura involves taking a drug history and a good family history, and ordering appropriate coagulation studies, tourniquet testing, and other tests. Referral to a hematologist is wise in obscure cases.

Other Useful Tests

1. CBC (aplastic anemia, leukemia, collagen disease)
2. Sedimentation rate (systemic infection, inflammation)
3. Coagulation time [hemophilia, disseminated intravascular coagulation (DIC)]
4. Partial thromboplastin time (hemophilia, DIC)
5. Bleeding time (vasculitis, vascular purpura)
6. Prothrombin time (liver disease, drug, etc.)
7. Platelet count (aplastic anemia, leukemia, collagen disease, ITP)
8. Rumpel–Leede test (vascular purpura, ITP, collagen disease)
9. Thromboplastin generation test (DIC, hemophilia)
10. Bone marrow examination (leukemia, aplastic anemia,, myelopthisic anemia)
11. ANA analysis (collagen disease)
12. Blood cultures (septicemia, DIC)
13. Coombs test (autoimmune disorders)
14. Monospot test (infectious mononucleosis)
15. CT scan of abdomen (neoplasm, splenomegaly)
16. Skin biopsy (Ehlers–Danlos syndrome, etc.)
17. Muscle biopsy (collagen disease)
18. Liver–spleen scan (metastasis, splenomegaly)
19. Bone scan (metastatic neoplasm).

Book Source Details

• Book Title: Differential Diagnosis in Primary Care
• Author(s): R. Douglas Collins
• Year of Publication: 2007
• Copyright Details: Differential Diagnosis in Primary Care, Copyright © 2007 Lippincott Williams & Wilkins.

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Copyright Details: Differential Diagnosis in Primary Care, Copyright © 2008 Williams & Wilkins.

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• Back to symptom: Thin skin: Introduction (review 99 causes)
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More About This Book: Title: Differential Diagnosis in Primary Care Authors: R. Douglas Collins Publisher: Lippincott Williams & Wilkins Copyright: 2007 ISBN: 0-7817-6812-8

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