Symplastic Atypia in Neoplastic and Non-neoplastic Endometrial Stroma: Report of 3 Cases With a Review of Atypical Symplastic Cells Within the Female Genital Tract:

Bizarre Chorionic-type Trophoblast in Second-trimester and Third-trimester Placentas: Clinicopathologic Characterization of a Placental Pseudoneoplastic Lesion

Bizarre (atypical/symplastic) cells have been described in various gynecologic normal tissues and benign neoplasms. This type of bizarre cytologic change is usually an incidental finding and is regarded as a benign process. We describe 17 cases of bizarre chorionic-type trophoblast in second-trimester and third-trimester placentas that created concern for an underlying/undersampled or incipient intraplacental trophoblastic neoplasm, predominantly found in intervillous trophoblastic islands (11/17), placental septae (6/17), chorionic plate (1/17), and/or the chorion layer of fetal membranes (2/17). The bizarre trophoblastic cells exhibited sheet-like or nested architecture, had a multifocal/patchy distribution, and/or were present as individual cells within hyaline stroma; they were characterized by large nuclei with smudgy chromatin and occasional intranuclear pseudoinclusions. The degree of atypia was classified as mild (0/17), moderate (3/17), or severe (14/17). Mitotic figures and necrosis were not identified. A dual immunohistochemical stain for trophoblast (hydroxyl-delta-5-steroid dehydrogenase) and a proliferation marker (Ki-67), performed in 15 cases, demonstrated 0% to very low proliferative activity within the bizarre trophoblast (0% to 2% [10/15], 3% to 8% [5/15]). Immunohistochemical stains for fumarate hydratase showed intact/retained expression in the bizarre cells in 7 of 7 cases. Clinical follow-up ranged from 1 to 45 months, and all patients were alive and well without subsequent evidence of a gestational trophoblastic or other neoplasms. We conclude that bizarre chorionic-type trophoblast in second-trimester or third-trimester placentas have the potential to mimic an intraplacental trophoblastic neoplasm but are likely a benign degenerative change. This study expands the spectrum of bizarre cells that occur in the gynecologic tract.

Pulmonary metastatic nodules of uterine low-grade endometrial stromal sarcoma: histopathological and immunohistochemical analysis of 10 cases

AIMS

To identify histopathological and immunohistochemical findings that aid diagnosis of metastatic endometrial stromal sarcoma (ESS) in small biopsy specimens of the lung.

METHODS AND RESULTS

We reviewed the histology of 46 lung nodules from 10 cases of pulmonary metastatic ESS. Biopsy sections were analysed by immunohistochemistry to highlight blood and lymphatic vasculature, and for expression of CD10 and oestrogen receptor (ER). Various histological changes were identified that could mislead in making a diagnosis on small biopsy samples: haemangiopericytomatous blood vessels (39%), absence of characteristic spiral arteriole-like vasculature (26%), intratumoral cysts formed by dilatation of airways (22%) or intratumoral myxoid change (11%), prominent interstitial collagen deposits (48%), foam cell infiltration (4%) and smooth muscle differentiation (2%). Peribronchial/peribronchiolar distribution of tumour cells with juxtaepithelial growth was a frequent feature, observed in 59% of nodules. In two very small nodules the lesion was barely recognizable histologically; tumour cells were detected only by expression of ER and CD10.

CONCLUSIONS

Combined staining for ER and CD10 can be helpful in avoiding an erroneous diagnosis. As lymphatics are not normally present in the juxtaepithelial bronchial/bronchiolar wall, juxtaepithelial tumour growth beneath the bronchial epithelium in early metastatic lesions indicates a haematogenous metastastic route through the bronchial artery.

Recent developments in uterine mesenchymal neoplasms

Smooth muscle and endometrial stromal tumours represent the two most common uterine mesenchymal neoplasms that may present diagnostic dilemmas for the practising surgical pathologist. Recent changes in morphological and staging criteria, as well as the discovery of new immunohistochemical markers, have improved the diagnosis and classification of these tumours. We highlight the difficulty in distinguishing tumour cell necrosis from infarct-type necrosis and the limited utility of p16 immunohistochemical expression in the diagnosis of leiomyosarcoma. We also discuss the controversial use of mitotic activity and necrosis as prognostic factors in endometrial stromal sarcomas. Emerging genetic information has also greatly expanded our understanding of 'sarcomagenesis' in both tumour types and may provide insight into potential therapeutic targets for the treatment of leiomyosarcoma and endometrial stromal sarcomas, harboring MED12 (mediator complex subunit 12) mutations and recurrent gene rearrangements, respectively. In this review, we discuss the core updates in the diagnosis and classification of uterine leiomyosarcomas and endometrial stromal sarcomas, highlighting new and important molecular genetic findings that may drive pathogenesis.

Paratesticular cellular angiofibroma with atypical (bizarre) cells: case report and literature review

We report the extremely unusual occurrence of a cellular angiofibroma (CAF) with atypical (bizarre) cells in the spermatic cord. We present a 63-year-old man, who was referred to the Urology Service with a six-month history of a slowly growing painless nodule in the right inguino-scrotal area. The clinical impression was that of a lipoma. The mass was locally excised. Gross examination showed a well-circumscribed neoplasm attached to the spermatic cord and measuring 5cm in the greatest dimension. Microscopic examination of the tumor showed the appearance of CAF with scattered severely atypical (bizarre) cells distributed throughout the lesion. By immunohistochemistry, atypical cells showed diffuse expression of p16, CDK-4, CD34 and vimentin. Keratin AE1/AE3, S-100 protein, p53, and epithelial membrane antigen were negative. The patient is free of disease two months after tumor excision. To the best of our knowledge, this is the third case of CAF with atypical (bizarre) cells occurring in the paratesticular area. Pathologists should be aware of this morphological variation of CAF to avoid misdiagnosis and over-treatment.

Desmoplastic Small Cell Tumor With Bizarre Giant Nuclei

A case is reported of an intra-abdominal desmoplastic small cell tumor featuring giant bizarre nuclei, an event not previously recorded in this entity to the best of the authors’ knowledge. The diagnosis was confirmed by immunohistochemistry and molecular genetics. A list is provided of the many other conditions in which this morphologically spectacular but clinically inconsequential nuclear change has been recorded.