Which physical findings are characteristic of complement deficiencies?

Updated: Apr 28, 2021
  • Author: Robert A Schwartz, MD, MPH; Chief Editor: Michael A Kaliner, MD  more...
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No specific physical findings are pathognomonic for complement deficiencies. Rather, clinical manifestations are representative of the infections and immune complex diseases to which patients are predisposed.

Because N meningitides is the overwhelmingly prevalent bacterial pathogen in these patients, knowledge of the physical characteristics of disseminated meningococcal disease is important. [20] The characteristic maculopapular rash that occurs in up to 75% of individuals with meningococcemia occurs soon after disease onset. The rash consists of pink lesions on the trunk and extremities; lesions are approximately 2-10 mm in diameter. The rash can quickly progress to hemorrhagic lesions. Petechiae are also a prominent finding and can occur on the skin of the trunk and extremities or on mucous membranes, such as the palate and conjunctivae.

Noninfectious diseases, such as SLE, that are associated with complement deficiencies can also have a characteristic physical presentation. Complement deficiencies associated with the deposition of immune complexes in various tissues can result in many of the sequelae of SLE, such as glomerulonephritis, arthralgia, uveitis, and vasculitic rash.

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