Blood parasite infection causing inflammatory reactions and benign formations in human thyroid gland

Abstract

A retrospective examining of cytology specimens obtained and verified by a fine-needle aspiration biopsy from patients with autoimmune thyroiditis and benign thyroid gland (cyst and goiter) formations allowed to note that in thyroid lobes they coincided in various combinations, thus rising a question about their potential etiological relation. In particular, a hemosporidian (blood parasitic) infection was found while analyzing cytology specimens from patients with autoimmune thyroiditis and benign thyroid gland (cyst and goiter) tumors prestained by Romanowsky-Giemsa dye. An evolution of developing intra-thyrocyte hemosporidia was tracked during a long-term detailed analysis of cytology specimens noted above. A panel of select specimens was stained (re-stained) with Schiff reagent according to the Feulgen method to clarify position of thyrocyte DNA and hemosporidian pathogens. Owing to an absorption approach, Romanovsky-Giemsa method allowed to repeatedly use specimens pre-stained with Schiff reagent according to the Feulgen method, wherein fuchsine was incorporated into DNA molecules after they were hydrolyzed by hydrochloric acid to stain specimens into magenta-lilac color. It allowed to identify a parasitic DNA inside developing hemosporidia most probably at exoerythrocytic stage and some erythrocytes cyst-based medusiform structures. Such technique used to stain specimens from patients with autoimmune thyroiditis allowed to localize the thyrocyte nuclear DNA as well as punctate and diffuse cytoplasmic inclusions of parasitic DNA, including magenta-lilac nuclei of different sizes inside erythrocytes. Thyrocyte nuclear DNA as well as punctate and diffuse hemosporidian DNA were distinguished in nodular goiter. Moreover, hemosporidian DNA was identified in a form of magenta-lilac multi-size nuclei inside erythrocytes. In contrast, unstained hemosporidian protoplasm was revealed as light-colored band around erythrocyte nuclei. The intra-erythrocyte nuclear hemosporidian material of different sizes may evidence about various species and/or pathogen generations. Intra-thyrocyte development of hemosporidian infection in patients with goiter results in marked cytoplasmic hyperplasia and its vacuolization associated with thyrocyte nuclear deformation, vacuolization, decreased size and degradation (with highly probability of mutations and deletions), reaching a pre-neoplastic level.

Keywords

• autoimmune thyroiditis
• cyst
• nodular goiter
• hemosporidian infection