IMAGES IN CYTOLOGY
Section Editor: Shahla Masood, M.D.
Pitfall in Sputum Cytology:
Protoctista Resembling Adenocarcinoma Cells
Rafael Martı ´nez-Giro ´n, M.D., Ph.D.1*and Andre ´s Ribas-Barcelo ´, M.D., A.P., C.P.1,2
The existence of various microorganisms, eukaryote in struc-
ture, that lack certain characteristics expressed in other King-
doms (animals, plants, and fungi) has resulted in the appear-
ance of the Protoctista Kingdom.1This Kingdom comprises a
diverse group of eukaryote microorganisms, grouped in vari-
ous Phyla, among which there are certain classes of algae,
such as Chlorophyta. The order of volvocales,2formed of
colonies of spherical cells (from 8, 16, 32, 64 up to 128) em-
bedded in a clear gelatinous matrix, belongs to this kingdom.
Each triangular-round cell contains a nucleus, more or less
central, a pyrenoid, and a contractile vacuole into which are
inserted two flagella. Freshwater colonies are widely distrib-
uted in pools, ditches, reservoirs, and lakes.
We describe in a sputum smear stained with the Papanico-
laou technique, and corresponding to a 68-yr-old-man who
presented various episodes of hemoptysis and with COPD
clinical antecedents, the presence of a contaminant, a proto-
ctista structure, catalogued as a Chlorophyte alga (presum-
ably Eudorina sp.). The moruliform disposition of the cells,
with very striking nuclei and the nonvisualization of the ge-
latinous capsule (Fig. C-1A), resembles certain types of Ade-
nocarcinoma. Under greater magnification, the existence of a
capsule and the presence of flagella in two cells (Fig. C-1B)
are suggested. To confirm the existence of the capsule, the
preparation was discolored and restained using the Peryodic
Acid Schiff (PAS) technique, evidencing the existence of a
PAS (+) structure surrounding all the cells in the form of a
capsule (Fig. C-2).
To catalogue this structure as a contaminant, the pres-
ence of inexistent structures in human cells such as con-
tractile vacuole, flagella, and a gelatinous capsule were
considered. Furthermore, with a careful microscopic exam-
ination of two consecutive samples corresponding to the
same patient, similar structures were not found.
We postulate that this peculiar contaminant came from
tap water used during staining procedure or due to a con-
tamination of the sputum in the oral cavity.
This case highlights the importance of considering
uncommon findings in cytological smears (artefacts and
contaminants) to avoid false positives and, with a care-
ful evaluation, establish a correct cytodiagnosis.
1. Scamardella JM. Not plants or animals: A brief history of the origin of
Kingdoms Protozoa, Protista and Protoctista. Int Microbiol 1999;2:
2. Nozaki H, Misawa K, Kajita T, Kato M, Nohara S, Watanabe MM.
Origin and evolution of the colonial volvocales (Chlorophyceae) as
inferred from multiple, chloroplast gene sequences. Mol Phylogenet
1Fundacio ´n INCLI´NICA, Calvo Sotelo, 16, 38DCHA, 33007 Oviedo,
2Servicio de Anatomı ´a Patolo ´gica, Hospital Universitario Central de
Asturias, Celestino Villamil S/N, 33006 Oviedo, Spain
*Correspondence to: Dr. Rafael Martı ´nez Giro ´n, M.D., Ph.D., Marque ´s
de San Esteban, 22-28B, 33206 Gijo ´n, Asturias, Spain.
Received 23 March 2006; Accepted 8 September 2006
Published online in Wiley InterScience (www.interscience.wiley.com).
Diagnostic Cytopathology, Vol 35, No 1
' 2006 WILEY-LISS, INC.
Fig. C-1. Protoctista structure in sputum smear. (A) cellular group with mor-
uliform appearance and very striking cell nuclei (Papanicolaou stain, 3400).
Leukocyte at the lower right corner is useful to compare diameters. (B) under
greater magnification two flagella (arrowed) are visible and the presence of a
capsule around the cells may be appreciated (Papanicolaou stain, 31000).
Fig. C-2. Peryodic Acid Schiff stain reveals the existence of a gelatinous
matrix surrounding the cells (PAS, 3400).
Diagnostic Cytopathology, Vol 35, No 1
PITFALL IN SPUTUM CYTOLOGY
Diagnostic Cytopathology DOI 10.1002/dc