Correct Answer: B. Sarcoidosis
The clinical triad of bilateral hilar lymphadenopathy (BHL), systemic symptoms (fever, night sweats), and neurological involvement (ptosis, bilateral facial nerve palsy) is pathognomonic for sarcoidosis. Sarcoidosis is a multisystem granulomatous disorder of unknown etiology that commonly affects the lungs and mediastinal lymph nodes in stage 1–2 disease. The bilateral facial nerve palsy is the key discriminator here—this represents Heerfordt syndrome (sarcoidosis with fever, parotitis, anterior uveitis, and cranial nerve involvement), a classic neurological manifestation of sarcoidosis. The leukocytosis reflects systemic inflammation. Sarcoidosis produces non-caseating granulomas on histology, distinguishing it from tuberculosis. The diagnosis is supported by elevated ACE levels, hypercalcemia, and elevated serum angiotensin-converting enzyme (ACE). In the Indian context, sarcoidosis is less common than TB but must be ruled out when non-caseating granulomas are found and TB is excluded. The combination of BHL + cranial nerve palsies (especially bilateral facial nerve) is virtually diagnostic of sarcoidosis and should trigger immediate consideration of this diagnosis over TB, which typically presents with unilateral hilar involvement and caseating granulomas.
Why the other options are wrong
A. Hypersensitive pneumonitis — Hypersensitivity pneumonitis presents with acute respiratory symptoms (cough, dyspnea) after antigen exposure and shows diffuse interstitial infiltrates, NOT bilateral hilar lymphadenopathy. It does not cause cranial nerve palsies or systemic constitutional symptoms like fever and night sweats. The absence of respiratory symptoms and presence of neurological involvement rules this out. C. Tuberculosis — While TB can present with fever, night sweats, and hilar lymphadenopathy, it typically causes unilateral hilar involvement with caseating granulomas on biopsy. TB does not cause bilateral facial nerve palsy or Heerfordt syndrome. The bilateral cranial nerve involvement and non-caseating granulomas (if biopsy were done) would distinguish sarcoidosis from TB—a critical NBE trap in endemic TB regions like India. D. Lymphoma — Lymphoma can present with fever, night sweats (B symptoms), and mediastinal lymphadenopathy, but it does NOT cause bilateral facial nerve palsy or the specific neurological syndrome described. Lymphoma typically shows asymmetric lymph node involvement and lacks the characteristic non-caseating granulomatous inflammation. The specific pattern of bilateral cranial nerve involvement is not typical of lymphoma.
High-Yield Facts
- Bilateral hilar lymphadenopathy (BHL) is the hallmark of sarcoidosis stage 1–2 and is present in ~90% of cases at diagnosis.
- Heerfordt syndrome = sarcoidosis with fever, parotitis, anterior uveitis, and cranial nerve palsies (especially bilateral facial nerve)—virtually diagnostic.
- Non-caseating granulomas on biopsy distinguish sarcoidosis from tuberculosis, which produces caseating granulomas.
- Elevated serum ACE (angiotensin-converting enzyme) and hypercalcemia are biochemical markers of sarcoidosis activity.
- Löfgren syndrome = sarcoidosis with BHL, erythema nodosum, and arthralgia—the most common acute presentation in India.
- Sarcoidosis commonly affects lungs (90%), skin (25%), eyes (25%), and nervous system (5%) in multisystem involvement.
Mnemonics
HEERFORDT Syndrome (Sarcoidosis Neuro Presentation) Hilar lymphadenopathy + Erythema nodosum + Eye involvement (uveitis) + Raised ACE + Fever + Other cranial nerves (facial nerve palsy) + Raised calcium + Dt (diagnosis = sarcoidosis). Use when you see bilateral facial nerve palsy + systemic symptoms + BHL. SARCOID (Multisystem Involvement Pattern) Skin (erythema nodosum) + ACE elevated + Respiratory (BHL) + Cranial nerves (facial palsy) + Ocular (uveitis) + Increased calcium + Diagnosis (non-caseating granulomas). Helps recall the classic presentation pattern.
NBE Trap
NBE pairs tuberculosis with hilar lymphadenopathy to trap students in endemic TB regions (India) into choosing TB reflexively. The key discriminator is bilateral facial nerve palsy and non-caseating granulomas—sarcoidosis, not TB, causes Heerfordt syndrome with cranial nerve involvement.
Clinical Pearl
In India, sarcoidosis is often missed because TB is the default diagnosis for any patient with fever, night sweats, and lymphadenopathy. The presence of bilateral cranial nerve palsies (especially facial nerve) should immediately trigger consideration of sarcoidosis and prompt ACE level testing and non-caseating granuloma biopsy to exclude TB before starting anti-TB therapy.
_Reference: Harrison Ch. 329 (Sarcoidosis); Robbins Ch. 8 (Granulomatous Inflammation); OP Ghai Ch. 12 (Connective Tissue Disorders)_