Noncaseating granulomas are the hallmark of sarcoidosis. Tissue is best taken from a superficial lymph node, but other described sites include lung and mediastinal biopsies when lymph nodes are not available. Studies by Marx and coworkers have shown that random biopsies of salivary gland tissue are very useful. Traditionally, labial biopsies have been used but a more effective site is the tail of parotid region. The incision is hidden behind the lobule and the procedure can be performed in the office setting using local anesthesia.
Serologic testing can support the diagnosis of sarcoidosis.
Again, no single test is diagnostic. The ACE level is the most useful test. The enzyme is concentrated within the pulmonary vasculature and is also found in bronchopulmonary lavage fluid, serum and cerebral spinal fluid. Another useful test is the gallium-67 scan. It is a more sensitive measure of pulmonary involvement than plain chest X-rays and can also detect subclinical disease in the parotid gland.