Cytologic Findings in Serous Effusion Specimens from Melanoma Patients.

INTRODUCTION: Metastatic melanoma (MM) is an uncommon finding in serous effusion specimens with a highly variable cytomorphology. METHODS: We reviewed specimens submitted over a 19-year period to determine (a) the range of cytologic findings in effusion specimens from melanoma patients and (b) the cytologic presentation and immunoprofile of MM in effusion specimens. RESULTS: Of 123 serous effusion specimens from patients with clinical notes of melanoma, 59% were reported negative for malignancy, 16% were reported with a non-melanoma malignancy, 19% MM, and 6% atypical, MM not excluded. Pleural fluids were twice as likely to be reported as MM than peritoneal samples. Review of 44 cases with confirmed MM showed the most common cytologic pattern was epithelioid. Most (88%) cases contained mainly dispersed plasmacytoid cells, but many (61%) also contained malignant cells arranged in loose groups. Rare cases also had spindle cells, giant bizarre cells, small lymphoid-like cells, or cells with large hard-edged vacuoles, mimicking other metastatic malignancies. MM cases containing predominantly plasmacytoid cells often mimicked reactive mesothelial cells. As well as being composed of cells of similar size, features such as bi- and multinucleation, round nuclei, mild anisokaryosis, nucleoli, and loose groups were common to both. Features seen more commonly in MM than reactive cells included large nucleoli (95%) and intranuclear cytoplasmic inclusions (41%), binucleate "bug-eyed demons," and small punctate vacuoles on the air-dried preparations. Pigment was identified in 36% of cases. Immunohistochemistry (IHC) is a valuable aid in confirming the cell type. The sensitivity for the most commonly used melanoma markers was as follows: S100 84% (21/25), pan-melanoma 100% (19/19), HMB45 92% (11/12), Melan A 92% (11/12), SOX10 91% (10/11). No staining was reported for calretinin (0/21), AE1/AE3 (0/11), EMA (0/16), Ber-Ep4 (0/13). DISCUSSION: Effusion specimens from patients with a history of melanoma are frequently (40%) malignant but almost as likely to be reported as a nonmelanoma malignancy as MM. The cytology of MM may mimic a wide range of other metastatic malignancies but also often closely resembles reactive mesothelial cells. It is important to be aware of this latter pattern so that IHC markers can be applied.

Opistholobetines (Digenea: Opecoelidae) in Australian tetraodontiform fishes.

Opistholebetine opecoelids are reported following examination of 1,041 individual tetraodontiform fishes, comprising 60 species and seven families, collected in Australian waters between 1986 and 2018. Nine species consistent with Opistholebes Nicoll, 1915, Heterolebes Ozaki, 1935 or Maculifer Nicoll, 1915 were recovered. However, phylogenetic analysis of sequence data, generated for some of these species, suggested that five genera, not three, are required to adequately accommodate these taxa. Thus, the concept and composition for each is revised, Pseudoheterolebes Yamaguti, 1959 nec Gupta, 1968 is resurrected and Parallelolebes n. g. is proposed. Of the nine species examined, five are new. Four new species are from fishes endemic to subtropical and temperate Australian waters for which no trematodes have previously been reported: Pa. australis n. sp. and Ps. corazonae n. sp. from the slender-spined porcupinefish Diodon nicthemerus Cuvier (Diodontidae) off Stanley, Tasmania; Pa. virilis n. sp. from the horse-shoe leatherjacket Meuschenia hippocrepis (Quoy & Gaimard) (Monacanthidae) off Stanley; and Ps. stellaglobulus n. sp. from the threebar pocupinefish Dicotylichthys punctulatus Kaup (Diodontidae) in Moreton Bay, south-east Queensland. The fifth new species is M. diodontis n. sp., collected from the spotted porcupinefish Diodon hystrix Linnaeus and the blackblotched porcupinefish D. liturosus Shaw, in tropical waters on the Great Barrier Reef. Species reported previously include the type-species of Opistholebes, O. amplicoelus Nicoll, 1915 from the rough golden puffer Lagocephalus lunaris (Bloch & Schneider) (Tetraodontidae) and the common toadfish Tetractenos hamiltoni (Richardson) (Tetraodontidae) in Moreton Bay, and three species reported for the first time from fishes in Australian waters: H. maculosus Ozaki, 1935, Pa. elongatus Ozaki, 1937 n. comb. and Ps. diodontis (Cable, 1956) n. comb., each from both D. hystrix and D. liturosus on the Great Barrier Reef. Following the revisions, Opistholebes is recognised for two species, Heterolebes for five, Maculifer for eight, Pseudoheterolebes for five and Parallelolebes for three.

Moravecia australiensis n. g., n. sp. (Dracunculoidea: Guyanemidae) from the gills of the green porcupine fish Tragulichthys jaculiferus (Cuvier) in Australia.

A new dracunculoid genus and species, Moravecia australiensis, is described from gill-filaments of the green porcupine fish Tragulichthys jaculiferus (Cuvier) (Tetraodontiformes: Diodontidae) from Moreton Bay, Queensland, Australia. Abundant mobile larvae and a few adult males with females occurred in the gill-filament between the epithelial basement membrane and efferent artery. Gills of all 69 fish examined contained larvae. Eleven harboured adult nematodes of a previously undescribed species belonging to the family Guyanemidae. The new species is placed within a newly proposed genus because it differs from the four existing genera in the family in possessing fine cuticular transverse striations, two forward protruding cephalic elevations, a circumoral elevation, a small triangular mouth surrounded by six cephalic papillae arranged in two lateral clusters of three each and a pair of large lateral amphids. Males have two pairs of pedunculate caudal papillae supporting the caudal alae. A key to the genera of the Guyanemidae is presented.