Which of the following statements about sarcoidosis are true: a) it has a high mortality rate (>50%); b) it is pathologically characterized by caseous granulomas; c) it presents with bilateral hilar lymphadenopathy on chest imaging; d) it commonly manifests as erythema nodosum; e) gallium‑67 scintigraphy can aid in diagnosis?

Sarcoidosis: Key Characteristics

The correct answers are c, d, and e—sarcoidosis characteristically presents with bilateral hilar lymphadenopathy on imaging, commonly manifests with erythema nodosum, and gallium scintigraphy can aid in diagnosis, while statements a and b are false.

Analysis of Each Statement

a. High Mortality Rate (>50%) - FALSE

Sarcoidosis does not have a high mortality rate. 1

• The disease has a generally favorable prognosis with most patients experiencing spontaneous remission or responding well to treatment
• Mortality is primarily associated with cardiac and neurologic involvement, but overall mortality remains low
• The presence of Löfgren's syndrome (bilateral hilar adenopathy with erythema nodosum and/or periarticular arthritis) is associated with particularly good prognosis 1

Critical caveat: While overall mortality is low, cardiac sarcoidosis carries significant mortality risk and requires aggressive monitoring, as it may present subtly with conduction abnormalities before progressing to life-threatening arrhythmias 2

b. Caseous Granulomas - FALSE

Sarcoidosis is pathologically characterized by non-caseating granulomas, not caseous granulomas. 1, 3, 4, 5

• The hallmark histopathologic finding is compact, tightly formed, non-caseating granulomas with large epithelioid histiocytes and multinucleated giant cells 3
• The absence of caseation is a key distinguishing feature from tuberculosis, which characteristically shows caseous (cheese-like) necrosis 3
• Negative microorganism stains and cultures are essential for diagnosis 3

Important pitfall: Some sarcoidosis cases may show a mixture of necrotic and non-necrotic granulomas, but this is atypical 1. The presence of caseation should prompt thorough exclusion of tuberculosis and fungal infections 3, 4

c. Bilateral Hilar Lymphadenopathy - TRUE

Bilateral hilar adenopathy is the most characteristic radiographic finding, present in approximately 90% of cases. 1, 2, 3, 6

• The American Thoracic Society classifies bilateral hilar adenopathy on chest X-ray, CT, and PET as a "highly probable" diagnostic feature 1
• The pattern is typically symmetrical and bilateral, involving both hilar and paratracheal lymph nodes 3, 6
• This finding is so characteristic that when combined with erythema nodosum (Löfgren's syndrome), it may not require histological confirmation 1, 2

Additional imaging features include perilymphatic nodules on chest CT and upper lobe or diffuse infiltrates 1, 2

d. Erythema Nodosum - TRUE

Erythema nodosum is a common clinical manifestation of sarcoidosis and is considered a "highly probable" diagnostic feature by the American Thoracic Society. 1, 2

• Presents as tender raised nodules typically on the shins 2
• Often associated with Löfgren's syndrome (bilateral hilar adenopathy with erythema nodosum and/or periarticular arthritis), which is so specific for sarcoidosis that it does not require histological confirmation 1, 2, 3
• Löfgren's syndrome is associated with excellent prognosis 1

Note: The question uses "nodular erythema" which appears to be erythema nodosum written in reverse order—this is a common clinical manifestation 1, 2

e. Gallium Scintigraphy - TRUE

Gallium-67 scintigraphy can aid in the diagnosis of sarcoidosis, particularly when showing characteristic patterns. 1, 7, 8

• The American Thoracic Society lists parotid uptake on gallium scan as a "highly probable" diagnostic feature 1
• Gallium-67 shows high uptake in cardiac sarcoidosis, with intensity correlating with degree of inflammation 1
• Distinctive patterns highly specific for sarcoidosis include:
  • Lambda sign: Intrathoracic lymph node uptake resembling the Greek letter lambda (present in 72% of sarcoidosis patients) 7, 8
  • Panda sign: Symmetrical uptake in bilateral lacrimal and parotid glands (present in 79% of sarcoidosis patients) 7, 8
  • The simultaneous presence of both lambda and panda signs (62%) is highly specific for sarcoidosis and may obviate the need for invasive diagnostic procedures 7, 8

Limitations: Gallium-67 has lower sensitivity compared to FDG-PET (which has 82-100% sensitivity and 39-91% specificity for cardiac sarcoidosis), though gallium scintigraphy remains included in imaging criteria 1

Summary of Correct Answers

• Statement c (bilateral hilar lymphadenopathy): TRUE 1, 2, 3, 6
• Statement d (erythema nodosum): TRUE 1, 2
• Statement e (gallium scintigraphy): TRUE 1, 7, 8