The majority of research on Histomonas meleagridis was performed in the first half of the last century, especially those on morphological aspects. In the present study identical monoxenic settings for cultures of the same H. meleagridis clonal strain in its virulent low passage and attenuated high passage form enabled a comparative analysis of parasite characteristics. For the first time, it could be shown that long-term in vitro cultivation led to a severe shift in cell morphology, with the occurrence of a very distinct phenotype expressing a flagellated and highly amoebic cell morphology. Furthermore, the attenuated parasites showed better growth rates and a higher tenacity when confronted with adverse conditions. During these experiments up to 100% of the parasites, both virulent and attenuated, assumed a completely rounded morphology elucidated by electron microscopy. The findings indicate that such previously reported cyst-like stages are a defence strategy of H. meleagridis, independent of the passage level in vitro and pathogenicity in vivo. In conclusion, long-term in vitro passaging of H. meleagridis led not only to an attenuation of the parasite, as previously demonstrated, but also to a shift in the parasite's phenotype regarding morphology, growth behaviour and a higher level of tenacity.

Surface sediments from six box cores along the north-eastern Antarctic Peninsula document the dinoflagellate cyst (= dinocyst) and other non-pollen palynomorph (NPP) content soon after overlying ice shelves collapsed. Prince Gustav Channel (PGC) and Larsen-A (LA) areas exhibited markedly different dinocyst abundances, concentrations being low in LA (0–20 cysts g-1) and high in PGC (2600–9100 cysts g-1, average: c. 3800 cysts g-1). Since similar water masses impact both areas, differences may be due to low biological productivity, limited sediment accumulation, and/or restricted fine-grain deposition at Larsen-A. Islandinium minutum (Harland & Reid in Harland et al.) Head et al. dominated dinocyst assemblages, occurring as both excysted and encysted forms (lesser abundance). Other taxa (Echinidinium cf. transparantum Zonneveld, Impagidinium pallidum Bujak, Bitectatodinium tepikiense Wilson, Operculodinium centrocarpum Wall & Dale, Brigantedinium spp., Selenopemphix antarctica Marret & de Vernal, Polykrikos? sp. A, and Polykrikos schwartzii Bütschli) were rare. Such assemblage composition is unusual compared to previously published Southern Ocean data, but may be specific to ice shelf and/or recently ice-free environments. Alternatively, it may be attributable to excessive production facilitated by environmental factors and/or abundant food, or similar cyst morphologies produced by different dinoflagellates. Accompanying NPPs included zooplankton remains, acritarchs, and freshwater algae. Tintinnid loricae were most abundant (max. 800 g-1), followed by foraminiferal linings (max. 320 g-1), and the acritarch Palaeostomocystis fritilla (Bujak) Roncaglia (max. 150 g-1). Collectively, NPPs were more abundant in PGC compared to LA samples.

A simple technique is described for preparation of Giardia cysts from faecal samples, the growth of trophozoites in suckling mice and the isolation of trophozoites for genetic analysis by allozyme electrophoresis. In total, 125 new isolates of Giardia have been collected from human and animal sources over a wide geographical area of South Australia and the Northern Territory of Australia. A number of long-established axenized isolates of G. intestinalis belonging to Groups I and II also adapted to grow in suckling mice. These findings indicate that suckling mice are permissive hosts for a variety of genetically dissimilar but morphologically similar organisms of the G. duodenalis type and that this in vivo technique may be less selective than isolation by in vitro culture. The use of suckling mice has revealed that infections can be composed of mixed genotypes and that isolation and purification techniques can be selective. Allozymic interpretation is essential to reveal the genetic complexity of such mixtures

A study of Leptomonas lygaei in Lygaeus pandurus is described. Flagellates with promastigote configuration were found in the midgut, ileum and rectum. Cysts and encysting stages (straphangers) were found in the rectum either attached to the flagella of promastigotes or free in the lumen. In the posterior midgut, the crypts were frequently filled with flagellates, but no attachment to host epithelium was observed. A close association between the flagellates and extracellular membrane layers was observed. In the rectum the flagellates frequently attached by hemidesmosomes to the cuticle of the gland cells and less frequently to the rest of the rectal wall. Interflagellar desmosomes between the expanded sheaths of flagella of adjacent parasites were also observed. Straphanger cysts attached to parental flagella by the formation of zonular desmosomes. Differences were apparent between the organelles of the encysting stages and the parental flagellates. In mature cysts, the cellular organelles were unrecognizable. A comparison between the cysts and flagellates of L. lygaei and Blastocrithidia familiaris is made.

Adult oysters Crassostrea gigas were experimentally fed with Alexandrium catenella and Alexandrium minutum which are responsible for recurrent toxic blooms in French coastal waters. C. gigas produced faeces and pseudofaeces containing intact and viable temporary pellicular cysts of these two Paralytic toxin producing species. When incubated in favourable conditions, these pellicular cysts were able to germinate at high rates (between 74 and 94%) and the resulting vegetative cells divided with growth rates close to the non- ingested cells (control). The toxin profile of the vegetative cells originated from the germinated temporary cysts was analyzed by liquid chromatography/fluorescence detection. Total toxin content of newly germinated cells was lower than that of cultured cells. Besides, cell contents of C2, B1, B2 and dcGTX3 toxins featured some changes. Our results suggest that the increased spreading of toxic dinoflagellates through the transfer of shellfish from contaminated towards pristine coastal areas cannot be ruled out. We also suggest that pellicular cysts and newly germinated cells could represent a potential way for the transfer of paralytic toxins toward the higher trophic levels.

The complications of concurrent chemoradiotherapy for nasopharyngeal carcinoma include dryness of mouth, sensorineural hearing loss, dental caries, trismus, pituitary dysfunction, myelitis, paralysis of cranial nerves IX–XII, massive neck fibrosis and pharyngeal wall necrosis. Tornwaldt's cyst formation after concurrent chemoradiotherapy for nasopharyngeal carcinoma has not been reported previously in the world literature. Tornwaldt's cyst, a persistent pharyngeal bursa, is found in about 3 per cent of the adult population, although the majority of these are asymptomatic. We describe the previously unreported complication of Tornwaldt's cyst formation after concurrent chemoradiotherapy for nasopharyngeal carcinoma.

Cystic lesions of the larynx are most commonly benign. However, we report a case of non-Hodgkin’s lymphoma (NHL) of the larynx which presented as a supraglottic cyst. This form of presentation has not been previously described in the medical literature.

Pre-tracheal air cysts or aeroceles are rare complications of tracheostomy. This is believed to be the first reported case in an adult presenting with a pre-tracheal air cyst 12 years after a tracheostomy. Only three case reports in children have been reported to date. The pathogenesis and treatment options are discussed and a method of managing this condition is suggested.

Arachnoid cysts (AC) often present with symptoms depending on their anatomical location within the skull; while supratentorial cysts grow causing relatively few symptoms, infratentorial ones may impair liquor circulation at the level of the fourth ventricle, giving rise to intracranial hypertension, or may stretch the complex nerve network in the cerebello-pontine angle. We report the singular clinical history of a 54-year-old male, who suddenly began to feel dizzy while sitting at his workplace, complaining of left tinnitus and aural fullness, in a classic clinical picture of Ménière’s disease. The anomalous findings at otoneurological examination (markedly the left deviation at the Fukuda test) made a magnetic resonance image (MRI) scan mandatory and a huge AC was found in the left fronto-parietal lobe. The mass provoked an evident clockwise rotation of the brainstem that we suppose to be the cause of acoustico-facial bundle stretching explaining the vestibular symptomatology.

Lateral saccular cysts have been diagnosed in 17 patients. Definitive diagnosis was made by computed tomography (CT) that showed a fluid-filled cystic swelling of the saccule with no air fluid level in all patients. Fifty-three per cent of cysts were bulging through the thyrohyoid membrane. They were hugely enlarged in 18 per cent, moderately enlarged in 24 per cent, and slightly enlarged in 12 per cent of patients. One patient (six per cent) showed bilateral cysts. Lateral saccular cysts were primary in origin in 82 per cent of patients and secondary to prolonged intubation, hemilaryngectomy, and laryngoscleroma in 18 per cent of patients. Surgical excision via a lateral cervical approach was performed in eight patients, whereas endoscopic CO2 laser vestibulectomy was performed in nine patients.

Endoscopic vestibulectomy with CO2 laser proved to be an efficient and safe procedure for excision of small and medium-sized cysts with a diameter equal to or less than 3 cm in the greatest dimension. The external approach appears more efficient than laser vestibulectomy in excision of huge cysts, as 22 per cent of patients undergoing laser surgery showed a recurrence.

We present a case of solitary cystic lymph node metastasis from an occult thyroid papillary carcinoma mimicking a lateral cervical cyst, and a case of thyroid papillary carcinoma with a true lateral cervical cyst. Based on a comparison of the radiographical findings of the two cases, differential diagnosis between cystic lymph node metastasis of papillary carcinoma and branchial cyst is discussed.

Porencephalic cyst expanding into the ear is a very rare complication of temporal bone fracture. We report a case of a 20 – year – old male who developed a traumatic porencephalic cyst of the temporal lobe expanding into the ear through a tegmen fracture in association with a cholesteatoma. The clinical presentation was otitic meningitis. This occurrence was not encountered in any of the cases reviewed in the literature. The diagnosis, pathogenesis, treatment and prognosis of this condition are reviewed.