Invasion of the thyroid gland is common in disseminated invasive aspergillosis. Large post mortem series have reported rates of thyroid involvement between 7% and 26% in disseminated disease (Young, 1970; Meyer, 1973; Fisher, 1981; Hori, 2002). In the majority of cases this is asymptomatic during life (Hori, 2002), although it is occasionally the primary manifestation of the disease (Hornef, 2000; Ayala, 2001).
When symptomatic, patients typically present with fever and tender thyroid enlargement, involving one or both lobes. Clinically the thyroid may be diffusely enlarged (Halazun, 1972; Ayala, 2001) or a nodule may be palpable (Lisbona, 1973; Torres, 1999). In one report thyroid enlargement occurred after one week of treatment with amphotericin B for invasive pulmonary disease (Kishi, 2002). Marked thyroid enlargement leading to fatal airway obstruction has been described (Cornet, 2001; Hori, 2002; Kishi, 2002), as has compression of the oesophagus leading to dysphagia (Sion, 2004). Evidence of dissemination to other organs may also be present at diagnosis (Lisbona, 1973; Keane, 1978). Histology of thyroid tissue usually demonstrates abscesses containing necrotic debris, haemorrhage and Aspergillus hyphae (Young, 1970). Vascular invasion with thrombosis and infarction is sometimes prominent.
Most patients remain euthyroid, but clinical and biochemical thyrotoxicosis has been reported, including cases where it has been the predominant feature (Hornef, 2000; Ayala, 2001). Hypothyroidism is more unusual, but has also been described (Hori, 2002).
In patients with symptomatic thyroid involvement, antemortem diagnosis has been made by microscopy or culture of FNA (Torres, 1999; Jang, 2004) or of surgically resected tissue. In one case a patient with fever and no localising symptoms had thyroid involvement detected by abnormal uptake on gallium scintigraphy (Matsui, 2006).
Medical treatment follows that of other forms of invasive aspergillosis. Surgery was also performed in several reported cases; either hemi- (Lisbona, 1973; Elzi, 2005) or total thyroidectomy (Hornef, 2000; Matsui, 2006). However, there are only a few reports of a successful outcome following treatment (Halazun, 1972; Jang, 2004), reflecting the high mortality of disseminated disease.
The reference section lists case reports of invasive aspergillosis where thyroid involvement was apparent during life, as well as postmortem series of patients with aspergillosis.
Dr Adam Jeans
Department of Infectious Diseases and Tropical Medicine, Pennine Acute Hospitals NHS Trust,
North Manchester General Hospital,