Pseudofungal tap water contaminants in sputum cytology

Abstract

Detection of contaminants in cytological smears, both intrinsic and extrinsic in origin, is an important aspect to take into account in the routine work that is carried out in Cytopathology laboratories. In many of them, tap water is commonly utilized in some steps of the Papanicolaou staining method such as hydration, rinse, and blueing. Because of its source in lakes and reservoirs, and under certain climatic circumstances (high temperatures and low rainfall), fresh water may suffer a phenomenon termed ‘‘Eutrophication’’ where, due to an overproduction of nutrients, an excessive growth of different microorganisms occurs. So, running tap water may be affected by a biological contamination and, occasionally, some types of microorganisms such as bacteria, algae, protozoa, worms, and arthropods may appear as contaminants in the cytological smears. Herein, different examples of contamination by four species of algae that were observed in sputum smears stained by the Papanicolaou method are shown. Due to their filamentous appearance, initially they were misinterpreted as uncommon fungal structures. Figure C-1A shows an elongated structure, in the shape of a chain, and consisting of 11 cylindrical/rectangular drum-like cells (10–40 3 5–20 lm in size). Each cell is joined to the next by its valvar surface. The dark tonality of the surface of some cells is due to siliceous material deposited thereon. These cells are held in a filament by means of a thin mucilaginous envelope. In this case, Melosira sp. (class Diatomeae) was the most-likely species to consider. These algae are very common in freshwater habitats, especially eutrophic waters. Because of their morphological features, this structure could be misinterpreted as arthrospores of Geotricum sp., a fungus that may cause respiratory infections in immunocompromised patients. However, arthrospores are much more rectangular in shape and less wide than alga cells, with rounded ends, variable sizes (6–12 3 3–6 lm), not always oriented in the same direction and they can appear scattered. Moreover, Geotricum produces hyaline septate hyphae which show dichotomous branching. In Figure C-1B, on a background with mucus, leukocytes, and some macrophages, there appears a very long unbranched filament (15–25lm in wide), bluish in color, with a thin cellular wall and dentated surface, formed by identical clear cells, rectangular or square in shape, and containing a round chloroplast. On the basis of these morphological features, this structure was tentatively identified as a filamentous green algae belonging to Ulothrix sp. This species is frequently found in cold oxygen-rich fresh waters, mainly in spring and summer. Absence of branching, spores, and budding phenomena are important points in order to reject the presence of fungal elements such as the conidiophore of diverse types of fungi. Figure C-1C shows a filamentous structure where the cells are connected end-to-end forming something similar to a chain. Vegetative cells (Antheridium) appear as short cylinders in shape (15–20 lm wide), and the bulb-like structures (Oogonium) located between the vegetative cells are egg cells. This structure was tentatively identified as a green algae belonging to Oedogonium sp. This species is widely distributed in all kinds of fresh water. In this case, Blastomyces dermatitidis, a fungus that can also cause pulmonary infections, should be taken into account for its differential diagnosis. The microscopic appearance of this dimorphic fungus may be like hyaline CFGS Anatomia Patologica y Citologia, Instituto de Piedras Blancas, Asturias, Spain *Correspondence to: Rafael Martinez-Giron, Ph.D., M.D., CFGS Anatomia Patologica y Citologia, Instituto de Piedras Blancas, Avda. Principal, 33. 33450-P, Plancas-Asturias, Spain. E-mail: rmartinezgiron@hotmail.com Received 7 March 2012; Revision 26 July 2012; Accepted 25 September 2012 DOI 10.1002/dc.22937 Published online 16 November 2012 in Wiley Online Library (wileyonlinelibrary.com).