Methimazole associated eosinophilic pleural effusion: a case report.
Adverse reactions associated to anti-thyroid drugs include fever, rash, arthralgia, agranulocytosis and hepatitis that are thought to be hypersensitivity reactions. Five cases of pleural effusion associated to thionamides have also been reported, two with propylthiouracil and three with carbimazole.



We report here a case of a 75-year-old man admitted because of unilateral pleural effusion. The patient had a recent diagnosis of hyperthyroidism and 6 days after starting methimazole complained of pleuritic chest pain. He had elevated C-reactive protein and erythrocyte sedimentation rate and normal white blood cell count and liver enzymes. Chest radiography showed a moderate right pleural effusion and the ultrasound revealed a loculated effusion that was shown to be an eosinophilic exudate.



The temporal relationship between methimazole intake and the development of pleural effusion combined with the extensive exclusion of alternative causes, namely infectious, neoplastic and primary auto-immune diseases, led to the diagnosis of hypersensitivity reaction to methimazole. The thionamide was stopped and corticosteroid was started with complete resolution of the pleural effusion in 3 months. Awareness of this rare adverse reaction of anti-thyroid drugs is important and methimazole can be added to the list of possible etiologies of drug-induced eosinophilic pleural effusion.
Serviço de Medicina 2, Hospital de Santa Maria - Centro Hospitalar Lisboa Norte, Avenida Prof. Egas Moniz, 1649-035, Lisbon, Portugal. pgasparcosta@gmail.com.
Pedro
P
Gaspar-da-Costa
Serviço de Medicina 2, Hospital de Santa Maria - Centro Hospitalar Lisboa Norte, Avenida Prof. Egas Moniz, 1649-035, Lisbon, Portugal.
Filipa
F
Duarte Silva
Serviço de Medicina 2, Hospital de Santa Maria - Centro Hospitalar Lisboa Norte, Avenida Prof. Egas Moniz, 1649-035, Lisbon, Portugal.
Júlia
J
Henriques
Serviço de Endocrinologia, Hospital de Santa Maria - Centro Hospitalar Lisboa Norte, Avenida Prof. Egas Moniz, 1649-035, Lisbon, Portugal.|Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal.
Sónia
S
do Vale
Serviço de Medicina 2, Hospital de Santa Maria - Centro Hospitalar Lisboa Norte, Avenida Prof. Egas Moniz, 1649-035, Lisbon, Portugal.|Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal.
Sandra
S
Braz
Serviço de Medicina 2, Hospital de Santa Maria - Centro Hospitalar Lisboa Norte, Avenida Prof. Egas Moniz, 1649-035, Lisbon, Portugal.|Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal.
João
J
Meneses Santos
Serviço de Medicina 2, Hospital de Santa Maria - Centro Hospitalar Lisboa Norte, Avenida Prof. Egas Moniz, 1649-035, Lisbon, Portugal.|Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal.
Rui
R
M M Victorino
D000368:Aged; D013956:Antithyroid Agents / Q000009:adverse effects*; D004804:Eosinophils / Q000187:drug effects* / Q000276:immunology; D006801:Humans; D008297:Male; D008713:Methimazole / Q000009:adverse effects*; D010996:Pleural Effusion / Q000139:chemically induced* / Q000175:diagnosis* / Q000276:immunology
D013956:Antithyroid Agents; D008713:Methimazole
Case report; Eosinophilic pleural effusion; Hypersensitivity reaction; Methimazole; Thionamides