Oxidized cellulose is a topical hemostatic agent that reduces postoperative bleeding. The polymer is deposited onto the surgical bed and is usually reabsorbed after 2 weeks. Complications due to incomplete absorption and foreign-body reaction with subsequent formation of pseudotumoral lesions are not uncommon (1). Fine-needle aspiration (FNA) cytology has demonstrated that it is capable of a specific recognition (1-4). This is an important observation because image studies do not allow precise diagnosis. In 2019, we reported our experience in 16 patients with pseudotumoral lesions of variable location induced by oxidized cellulose (Surgicel®). Since that study, we have seen many other cases in different locations, most commonly following thyroidectomy. In this report, we would like to share a peculiar case seen in the tracheostomy scar of a post-COVID19 patient who had previously undergone invasive mechanical ventilation. The pseudotumoral lesion mimicked a thyroid nodule. We have found no previous reports in the medical literature describing this complication after tracheostomy procedures. Unfortunately, the COVID19 pandemic has increased the number of patients with tracheostomy scars, and it is important for clinicians and pathologists to be aware of this complication.
The patient, a 74-year-old woman was been followed because of hypothyroidism. An ultrasonographic study revealed a suspicious left 14.8 mm thyroid nodule (Fig. 1) and FNAC was performed. During FNA, we noted the presence of a tracheostomy scar. The patient mentioned that two years earlier, she suffered from pulmonary COVID19, which required 12 days of invasive mechanical ventilation. We reviewed the clinical history and found that oxidized cellulose (Surgicel®) was used during the tracheostomy closure procedure. The time interval between Surgicel ® use and FNAC has been 31 months. Cytologic smears were air-dried and stained with Diff-Quik. They showed a deeply intense background resembling colloid, in addition to numerous macrophages, and the characteristic slender, quadrangular structures that sometimes showed a laminated appearance. Under polarized light, brilliant birefringence was observed in the well-preserved quadrangular fragments (Fig. 2). There were no follicular thyroid cells nor acute inflammation. Following the pathological result, the radiologists reviewed the thyroid ultrasound and found that the nodule was not in fact intra-thyroid but was in intimate continuity.
Cytology has demonstrated that it is capable of a specific recognition of pseudotumoral reactions induced by oxidized cellulose (1-4). Cases that simulate tumor recurrence have been described after almost all types of surgical procedures in which this hemostatic agent has been used. The differential diagnosis is mostly limited to other exogenous substances known to induce a granulomatous reaction and was discussed in our previous study (1). In this context suture granuloma must be considered. They are reported as showing an intense inflammatory reaction in which exogenous material is not always identified. The suture material is scarce, and the fragments are less uniform and do not show the regular morphology of oxidized cellulose (5). It is important to mention that in cases concerning the thyroid surgical bed, Surgicel ® can mimic dense colloid, especially if the typical quadrangular structures are scarce. Identification is greatly facilitated by a history of previous thyroidectomy. Our patient and others like her will not have such a history and this could make the diagnosis more difficult. Therefore, the detection of the tracheostomy scar is important as it would justify the use of a hemostatic agent. The absence of follicular cells and presence of numerous macrophages phagocytizing the material should raise suspicion of a foreign body reaction. The importance of the case reported lies in its relation to COVID19. The number of patients requiring invasive mechanical ventilation and tracheostomies has been very high. Therefore, we believe that the phenomenon we describe is likely to be observed more frequently and should be added to the list of potential long-term post-COVID19 sequelae. The presence of a tumor lesion near a tracheostomy bed should raise the possibility of this complication and alert pathologists to the possibility of reaction to hemostatic agents.