Acute suppurative thyroiditis (AST) leading to thyroid abscess is a rare clinical entity. Thyroid abscess and AST represent only 0.1 to 0.7% of surgically treated thyroid pathologies.1 AST affects specially patients with pre-existing thyroid gland pathology and in childhood is associated with local anatomic defects.2 It has been reported that the pyriform sinus fistula (internal fistula) is the route of infection and is the most common underlying abnormality in the patient with AST.3 Because of its rarity and unusual clinical features, the diagnosis of suppuration in thyroid gland is often delayed. Progress to abscess formation may then occur with all the inherent dangers of advanced suppuration in the neck. Thyroiditis resulting in skin sinus is very rare. Tuberculous lymphadenitis or tuberculous thyroiditis may result in skin sinus, however, inflammatory thyroiditis leading to skin sinus is rare.

We present a case of skin sinus communicating with left lobe of thyroid. This case is reported because of the rarity of the condition.

We present a case of 35 years old female who presented to us with swelling in the neck since 4 years. Swelling in the beginning was painful, associated with fever and later bursted open on to the skin with discharge of purulent fluid. Patient took treatment from a local doctor for the same. No details regarding medication was known. Presently patient was complaining of discharge from the skin sinus off and on since last 3 years.Patient had no history of kochs or kochs contact. Clinical examination revealed a skin sinus on the left side of midline in the neck with an underlying swelling measuring 3 cms X 3 cms moving well with deglutition and not on protrusion of the tongue. A provisional diagnosis of tuberculous sinus from paratracheal lymph nodes was made. Routine investigations ruled out tuberculosis. Fine needle aspiration cytology showed inflammatory sinus. However, Ultrasonography of the neck revealed skin sinus communicating with the left lobe of thyroid. Patient was euthyroid on investigation. She was worked up for surgery . Intra-operative findings confirmed skin sinus communicating with the left lobe of thyroid. There was no communication with pyriform fossa. Left lobe of thyroid along with skin sinus was excised en-masse (Fig. 1). Histopathology of the specimen showed infected sinus tract arising from the thyroid showing mixed inflammatory cell infiltrate and entrapped follicles containing scanty colloid. Post-operative recovery was uneventful.

Fig. 1 : Specimen showing skin sinus communicating with left lobe of the thyroid removed en-masse.

Primary thyroid abscess resulting from acute suppurative thyroiditis (AST) is an unusual type of head and neck infection. The ability of the thyroid gland to resist infection is well known and inflammatory pathologies of the thyroid such as AST are uncommon. The frequency with which this proceeds to abscess formation is rare particularly with the advent of widespread usage of antibiotics. In a review of literature by Schweitzer and Olson4 in their publication in 1981, have noted that only 39 cases of thyroid abscess had been reported in the medical literature since 1950, of which 16 were in children.

The remarkable resistance of the thyroid gland to infection is attributed to many factors. A prosperous lymphatic and vascular supply, well developed capsule, high iodine content of the gland are various mechanisms suggested to account for this relative resistance to infection.4,5 Since the gland has no external connections the route of infection was a mystery. In 1978, Takai et al reported 15 patients with AST where a pyriform sinus fistula was the apparent route of infection.6 The pyriform sinus fistula is an internal pharyngeal fistula and has been shown to be the most common underlying abnormality in patients with AST.3 The fistula ends in or adjacent to the thyroid and allows bacterial infection to develop in or around the gland. The left side is more commonly involved than the right. Treatment includes incision and drainage of the abscess or partial thyroidectomy depending upon the presence or not of underlying thyroid pathologies. It is absolutely necessary to eliminate the source of infection-often a pyriform sinus fistula whose total resection effectively prevents a relapse. In our case intra-operative findings ruled out any communication with pyriform fossa. Patient had uneventful recovery. We conclude that skin sinus due to thyroiditis is a clinical rarity and requires complete excision of the thyroid lobe and skin sinus en-masse.