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Rare forms of thyroiditis

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Acute purulent thyroiditis

This is a very rare disease. Patients in a poor general condition and immunocompromised patients are generally affected (Volpe 1978). The cytologic picture is characterized by neutrophils and cellular debris. We did not met any patients with diffuse, acute thyroiditis.

It may be debated that an abscess in a thyroid nodule belongs to this category. Nevertheless, the cytological presentation is the same. A few cases has occurred in our practice, and all patients were in a patient in an excellent clinical condition without any known predisposing factor. We met patients with fever but also without fever. Similarly, pain is not necessary. This form is acute thyroiditis may be caused by a developmental disorder, i.e. the lack of closing the thyroglossal cyst which may predispose to spreading a neck or lymph node infection to the thyroid. Patient with this condition presented hypoechogenic, cystic nodules. The aspiration of the necrotic-purulent material and antibiotics is the choice of treatment. If the abscess recurs than surgical procedure is indicated.

Riedel's thyroiditis

This extemely rare disease is a clinico-pathological entity presenting with a hard goiter extending to the surrounding connective tissue and neck muscles. This leads to complete replacement of the thyroid by fibrous tissue (Orell 1997). Droese mentioned three cases in his handbook, and stated that the disease cannot be diagnosed cytologically (Droese 1995). There is general agreement in the literature that a suspicion of the entity is an indication for surgical exploration.

We met two patients with Riedel's thyroiditis. Both presented a stone-hard, extremely hypoechogenic thyroids with echogenicity close to a cyst. Gaining cytological material was unsuccessful. The painless mass evolved over weeks in both cases.

Repeated surgical ablation and steroid therapy for two years resulted in remission lasting for more than 9 years in the first case. The second patient was lost for follow-up after surgery.

Granulationaround surgical thread

This entity is not mentioned in the cytological textbooks known to us. We describe it here because it has a characteristic clinical and cytological presentation. The first sign is a very firm nodule that suddenly develops in the region of the thyroid years or even decades after surgical exploration of the thyroid. The mean time between the surgery and the appearance of the nodule in our 38 cases was 4.4 years. It not infrequently causes great fear for the patient, and even for general practitioners. The lesion may appear relatively distant from the scar line. Around two-thirds of our patients presented without pain, and all of them were afebrile.
The sonographic presentation may cause concern: a hypoechogenic lesion with irregular hyperechogenic granules or patches is close to the appearance of a medullary carcinoma. The lesion is always avascular.

The cytological picture is characterized by the presence of neutrophils, multinucleated giant cells, histiocytes and (as a pathognomic sign) debris of surgical thread. If it causes complaints for the patient, we advise surgical excision.

Subacute thyroiditis-like reaction in patients previously treated with ethanol injection for thyroid nodules

PEI treatment is relatively new modality in cases of autonomously functioning thyroid nodules, thyroid cysts and even in non-toxic nodules. We observed a subacute-like reaction in 19 of 483 patients treated with ethanol. All of the patients had a clinical presentation similar to that of subacute de Quervain`s thyroiditis, including enlarged, painful, hard thyroids that suddenly developed  on the treated side within 24 hour of the last ethanol session. The ESR was elevated in 3/4 of our cases. A 2-week course of steroid treatment was effective and, in contrast with de Quervain`s thyroiditis, no relapse occurred. Damage to the extranodular thyroid by ethanol is the most possible cause of this entity, which is not described among the side-effects of PEI treatment in the literature. We might mention that 7 patients affected had stayed for hours in bright sunshine the day before the sudden onset of the complaints.

The sonographic presentation is characteristic. The treated nodule and it's environment becomes hypoechogenic. The borders of the inflamed area is ill-defined, the vascularization is absent.

The cytological picture was not characteristic. We could aspirate adequate material in only two cases. A mixed inflammatory reaction with neutrophils, lymphocytes, amorphous, necrotic material, and some clusters of degenerated follicular cells could be observed.

This reaction has a very favourable consequence: in most patients the treated nodule will decreasing without any further sessions.

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