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Q1: What does the computed tomogram of the thorax show?
The computed tomogram (see p 512) demonstrated enlarged mediastinal and bilateral hilar lymph nodes.
Q2: What is the most probable diagnosis?
The clinical and radiographic features are consistent with the diagnosis of sarcoidosis. The cause of hoarseness is due to left vocal cord palsy as a result of compression of the left recurrent laryngeal nerve by enlarged mediastinal lymph nodes. Other differential diagnoses to be considered are lymphoma and tuberculosis.
For this patient a mediastinal lymph node biopsy was performed by mediastinostomy. This revealed numerous granulomas consisting of epithelioid cells and lymphocytes. Foci of caseation necrosis were present. Stains for acid-fast bacilli and fungi were negative.
Q3: Describe the three mechanisms causing hoarseness in this condition
Compression of the left recurrent laryngeal nerve by enlarged mediastinal lymph nodes is not the only mechanism of hoarseness in sarcoidosis. Hoarseness in sarcoidosis may also be due to granulomatous infiltration of the larynx, which is identified in about 5% of patients.1 Sarcoid cranial polyneuropathy involving the vagus nerve may also lead to dysphonia. This situation is often associated with other neurological lesions, in particular facial nerve palsy.
The left recurrent laryngeal nerve originates from the vagus nerve and progresses below the aortic arch, then ascends to the vocal cord. In the thorax the left recurrent laryngeal nerve travels in close proximity to the aorta, left atrium, trachea, left main bronchus, oesophagus, and the mediastinal lymph nodes. Diseases affecting any of these structures may lead to nerve palsy and subsequent left vocal cord paralysis. Unilateral vocal cord palsy usually presents with hoarse voice due to inadequate compensation by the contralateral vocal cord.
Vocal cord paralysis is an unusual complication of sarcoidosis. There have been few reports of sarcoidosis with mediastinal lymphadenopathy compressing on left recurrent laryngeal nerve leading to left vocal cord palsy and hoarseness of voice.1-4
Conventional chest radiography reveals evidence of intrathoracic lymph node enlargement in 75% to 85% of patients with sarcoidosis.5 It is usually localised to the hilar, tracheobronchial, and paratracheal groups and typically is bilateral and symmetrical. The aortopulmonary lymph nodes are involved in 75% of 62 patients with sarcoidosis and intrathoracic lymphadenopathy in one review.6 In this patient, computed tomography demonstrated intrathoracic lymphadenopathy involving all the mentioned groups of lymph nodes.
The pathological hallmark of sarcoidosis is the granuloma. The majority of granulomas are non-caseating. However, as in this patient, some granulomas contain foci of caseation, the presence of which does not exclude the diagnosis.7 Such caseation typically occurs in the central portion of the granuloma and appears as amorphous eosinophilic material often associated with degenerated, hyperchromatic nuclei. In a review of 100 patients with hepatic sarcoidosis,8 granulomas with central caseation were noted in 1% of the cases.
This patient was treated with corticosteroid. His symptoms improved rapidly with resolution of his hoarseness and dry cough. The 24 hour urine calcium concentration fell to normal at 5.8 mmol/24 hours. Resolution of the left vocal cord paralysis was confirmed by a repeat laryngoscopy two months later. A repeat computed tomogram of the thorax eight months later revealed marked regression of the mediastinal lymphadenopathy.
Sarcoidosis with left vocal cord paralysis due to compression of left recurrent laryngeal nerve by enlarged mediastinal lymph nodes.
Hoarseness can be a presenting complaint in sarcoidosis which may be the result of left vocal cord palsy due to compression of the left recurrent laryngeal nerve by enlarged mediastinal lymph nodes.
Pathological finding of granulomas with central caseation does not exclude the diagnosis of sarcoidosis.