Fine-needle aspiration cytology of pulmonary adenocarcinoma of fetal type: report of a case with immunohistochemical and ultrastructural studies

Cytomorphology of pulmonary low-grade fetal adenocarcinoma in bronchial brushing specimen prepared by BD SurePath: A case report and literature review

Low-grade fetal adenocarcinoma (LGFA) of the lung is a rare subtype of lung adenocarcinoma, resembling developing fetal lung in pseudoglandular stage. LGFA is very different to conventional adenocarcinoma. It is more likely to occur in young adults and has favorable prognosis. Reports on the cytology of LGFA are very rare; only 10 cases have been reported previously in the English literature. Our case report adds to the cytological features of this tumor sampled by bronchial brushing and is the first case prepared by the BD SurePath liquid-based cytology. We present a case of 31-year-old male with endobronchial involvement of right bronchus. The cytological features of diagnostic clues for LGFA include three dimensional glandular arrangements of uniform, columnar cells with inconspicuous nucleoli. It is important to recognize this rare and favorable variant of lung adenocarcinoma. In this report, we present the cytological and pathological features of LGFA, along with a literature review.

Comprehensive review of fetal adenocarcinoma of the lung

Fetal adenocarcinoma of the lung (FLAC) is a rare tumor. It accounts for ~0.1%-0.5% of all pulmonary neoplasms. Due to its rarity, much of the world literature regarding FLAC comes from case reports and case series. FLAC is an adenocarcinoma resembling developing fetal lung in its pseudoglandular stage (8-16 weeks of gestation). It is distinguishable from pulmonary blastoma (PB) because it lacks the mesenchymal component which is a hallmark finding in PB. Due to differences in histopathology and clinical course, FLAC has been further categorized into low-grade (L-FLAC) and high-grade (H-FLAC) forms. L-FLAC displays low nuclear atypia and prominent morule formation and has a pure pattern. H-FLAC typically presents with at least 50% fetal morphology, and is often associated with other conventional types of lung adenocarcinoma. FLAC expresses neuroendocrine markers and thyroid transcription factor 1 in most cases. L-FLAC has an aberrant nuclear/cytoplasmic expression of β-catenin and presents mutations in this gene. H-FLAC overexpresses p53. These tumors have a very low frequency of mutations in KRAS and EGFR; it is thought that they are different from a molecular point of view to conventional lung adenocarcinomas. Approximately 25%-40% of patients are asymptomatic at presentation; most of them are incidental findings on chest radiographs. H-FLAC is more common in elderly male patients, with a heavy smoking history. L-FLAC tends to occur in young females. Patients with L-FLAC are usually diagnosed with stage I-II disease, while patients with H-FLAC usually present with a more advanced-stage disease. Poor prognostic factors for FLAC are thoracic lymphadenopathy, metastases at diagnosis, and tumor recurrence; however, the 10-year survival for FLAC is estimated at 75%.

Well-differentiated fetal adenocarcinoma of the lung mimicking adenoid cystic carcinoma on fine needle aspiration: A case report

Well-differentiated fetal adenocarcinoma (WDFA) of the lung is a rare variant of adenocarcinoma with an unusual morphology. Although the histologic features of this rare neoplasm have been well established, there is a deficit in the literature with regards to its discrete cytomorphologic features. We report the fine needle aspiration (FNA) findings of a case of this unusual malignancy in a 44-year-old man with an incidental lung nodule. FNA revealed three-dimensional clusters of epithelial cells with scant cytoplasm, hyperchromatic nuclei that are associated with an extracellular metachromatic matrix. The original cytology report was signed out as an epithelial neoplasm favor adenoid cystic carcinoma. Consequently, a wedge resection of the lung was done and the histologic diagnosis was WDFA of the lung. The findings of minimal nuclear atypia in association with focally abundant spheres of extracellular matrix can mimic adenoid cystic carcinoma. WDFA has good prognosis and therefore, pre-operative cytologic diagnosis is critical to clinical management. We present the cytomorphologic features of this neoplasm with particular emphasis on a potential diagnostic pitfall of this rare entity. Diagn. Cytopathol. 2016;44:917-920. © 2016 Wiley Periodicals, Inc.

Aspiration cytomorphology of fetal adenocarcinoma of the lung

Fetal adenocarcinoma (FA) of the lung is an exceedingly rare malignancy. Many patients with the well-differentiated form are relatively young and with the high-grade variant are older. We describe the cases of 4 women with FA examined by fine-needle aspiration biopsy. Aspirates were moderately cellular with malignant, mostly aggregated cells. Glands and acini were present. The columnar neoplastic epithelial cells had homogeneous round nuclei with fine chromatin, smooth membranes, and indistinct nucleoli. With the rapid Romanowsky stain, subnuclear vacuoles were evident in some tumor cells; at times, this was associated with a focal extracellular tigroid pattern. Morule formation was present in the 3 specimens. Immunochemically, all tumors manifested epithelial and neuroendocrine differentiation. Cytomorphologic attributes included the following: (1) distinct subnuclear vacuoles, sometimes with an associated tigroid picture; (2) small, uniform, round nuclei; (3) morules; and (4) neuroendocrine differentiation in glandular epithelial cells.

Sarcomatoid neoplasms of the lung and pleura

Sarcomatoid neoplasms of the lung and pleura are rare tumors that present a complex differential diagnosis, making them challenging for surgical pathologists. In the lung, the main tumors are the sarcomatoid carcinomas, including pleomorphic carcinoma, spindle cell carcinoma, giant cell carcinoma, carcinosarcoma, and pulmonary blastoma. They are characterized by histologic heterogeneity; molecular data support their origin from a pluripotent stem cell that undergoes neoplastic transformation with divergent epithelial and sarcomatous differentiation. Diagnosis is difficult in small biopsy specimens and typically requires a resection specimen. Despite the presence of sarcomatoid features, these tumors are classified as lung carcinomas. Pulmonary blastomas must be distinguished from pleuropulmonary blastomas, which are a unique type of thoracic sarcoma typically occurring in young children. In the pleura, the main tumors to consider are the sarcomatoid and desmoplastic types of malignant mesothelioma, solitary fibrous tumor, and desmoid tumor. While light microscopy is sufficient to diagnose most of these tumors, immunohistochemistry can be useful in selected settings. In particular, it can aid to confirm epithelial differentiation in spindle cell carcinomas and the presence of rhabdomyosarcoma in sarcomatoid carcinomas, mesotheliomas, or pleuropulmonary blastomas. For sarcomatoid and desmoplastic mesothelioma, keratin is the most useful stain because it can highlight invasive growth and mesothelial markers are positive in only the minority of cases. Clinical and radiologic correlation is needed to separate some pleomorphic carcinomas with pleural involvement from sarcomatoid malignant mesothelioma, since these poorly differentiated tumors may not express the usual immunohistochemical markers for carcinoma or mesothelioma.

Well-differentiated fetal adenocarcinoma of the lung: Cytomorphologic features on fine-needle aspiration with emphasis on use of β-catenin as a useful diagnostic marker

Well-differentiated fetal adenocarcinoma (WDFA), also known as low grade adenocarcinoma of the fetal lung type, is a rare pulmonary neoplasm now considered to be a variant of lung adenocarcinoma rather than a type of pulmonary blastoma. Upregulation of the Wnt signaling pathway with subsequent aberrant nuclear/cytoplasmic beta-catenin expression has been recently described in these tumors providing a possible pathogenetic role for this gene in WDFA. We describe the cytomorphologic findings of a case of WDFA in a 36-yr-old female patient and emphasize the diagnostic utility of aberrant nuclear/cytoplasmic expression of beta-catenin as an adjunct to the correct preoperative recognition of this tumor on aspiration cytology.

Alpha-fetoprotein-producing lung carcinoma: report of three cases

Three cases of alpha-fetoprotein (AFP)-producing lung carcinoma were studied histologically and immunohistochemically. Samples were obtained from two men and one woman who ranged in age from 64 to 71 years. Serum AFP levels for the three samples were 9826, 74.4 and 24.3 ng/mL. One case was classified as stage IIIA and two as stage IIIB. Two cases were diagnosed as large cell neuroendocrine carcinoma, and AFP expression was detected immunohistochemically. One of these samples showed differentiation to a hepatoid carcinoma, while the other was combined with a squamous cell carcinoma. The remaining case was a squamous cell carcinoma, and AFP was detected in only some of the tumor cells. All patients died within 2 years. The Ki-67 labeling indices of the AFP-producing pulmonary carcinomas (30.2 +/- 4.6%) were significantly higher than those of AFP-negative pulmonary carcinomas (P < 0.05). The high proliferative activity, advanced stage at presentation, vascular endothelial growth factor expression and vascular invasion observed in these tumors may explain the poor prognosis of AFP-producing lung carcinomas.

Diagnostic dilemmas in pulmonary cytology

BACKGROUND

Diagnostic difficulties in pulmonary cytology may be compounded by other medical problems, lack of pertinent information, and the presence of rare tumors. In the current study, the authors describe six cases of lower respiratory tract cytology that presented particular diagnostic challenges or pitfalls.

METHODS

Three lung fine-needle aspiration biopsies (FNAB) from three patients, four bronchoalveolar lavages from two patients, and one bronchial washing from one patient, each with histologic confirmation, were reviewed. Cytologic material included direct smears, ThinPrep slides, and cell blocks. Cytologic findings were compared with established cytologic criteria for each final diagnosis.

RESULTS

Two cases with Aspergillus infection that demonstrated reactive atypical cells were misinterpreted as squamous cell carcinoma and nonsmall cell carcinoma. Two cases diagnosed as significant atypia and negative, respectively, subsequently were found to show bronchioloalveolar carcinoma (as well as lymphangioleiomyomatosis, which was suspected clinically) and bronchogenic adenocarcinoma, respectively. One lung FNAB from a patient subsequently confirmed to have bronchiolitis obliterans-organizing pneumonia (BOOP) showed reactive pneumocytes that initially were misinterpreted as being suspicious for carcinoid. These reactive pneumocytes were identified histologically in the area of BOOP. The last case was an FNAB of a well differentiated fetal-type adenocarcinoma, an unusual variant of adenocarcinoma that to the authors' knowledge rarely is described in the cytology literature.

CONCLUSIONS

Cytomorphologic features of lower respiratory tract pathology combined with appropriate clinical information and diagnostic discretion usually allow accurate diagnoses and should decrease both false-positive and false-negative result rates. Clinical information and radiologic findings may be invaluable, but may not always parallel the cytologic diagnosis.

Pulmonary adenocarcinomas of the fetal lung type: a clinicopathologic study indicating differences in histology, epidemiology, and natural history of low-grade and high-grade forms

Seven cases of high-grade adenocarcinoma of fetal lung type (H-FLAC) are compared with nine cases of pulmonary endodermal tumor resembling fetal lung or low-grade adenocarcinoma of fetal lung type (L-FLAC). Of the seven patients with of H-FLAC, four were men and three were women. All of the patients but one were in their 60s or 70s. Five patients were smokers. After resection of the tumor, three patients died of metastases, two patients are alive with no evidence of disease, and two patients died of a postoperative complication. Histologically, H-FLAC and L-FLAC have both complex glandular structures resembling fetal lung and neuroendocrine differentiation. Two cases of H-FLAC had stromal proliferation typical of biphasic pulmonary blastoma. The H-FLAC was distinguished from L-FLAC by the presence of disorganized glands, large vesicular nuclei, prominent nucleoli, pronounced anisonucleosis, absence of morules, transition to conventional adenocarcinoma, broad areas of necrosis, desmoplastic stroma, overexpression of p53 protein, and production of alpha-fetoprotein. High and low grades of FLAC explain discrepancies in previously reported clinicopathologic features of FLAC. The H-FLAC needs to be distinguished from L-FLAC. Both forms may have stromal components, so both have been referred to as blastomas. The H-FLAC represents the prototype of so-called pulmonary blastoma predominantly seen in the elderly, whereas L-FLAC and its biphasic form predominate in the middle-aged population.

Hepatoid adenocarcinoma of the lung: report of a case of an unusual alpha-fetoprotein-producing lung tumor

We report on a rare tumor of the lung characterized by its morphologic hepatoid features and alpha-fetoprotein production. This unusual neoplasm arose in the left lung of a 36-year-old man in whom clinical and radiologic examinations did not reveal any other tumor. The serum level of alpha-fetoprotein was measured at 6,090 ng/mL and was parallel to the evolution of the tumor. Despite treatment, the patient died 7 months after the diagnosis. The microscopic appearance of the tumor was the same as observed in hepatocarcinoma and hepatoid adenocarcinoma of the ovary or the stomach, with a tubular, papillary, or trabecular pattern. Periodic acid-Schiff-positive hyaline globules were numerous, and tumor cells showed immunohistologic positivity for alpha-fetoprotein and carcinoembryonic antigen. This lung adenocarcinoma was first described by Ishikura et al. in 1990 and was named hepatoid lung adenocarcinoma. Like the rare hepatoid carcinoma of the gallbladder, the pancreas, the ampulla of Vater, the renal pelvis, and the bladder, the exact histogenesis and the prognosis of this type of lung tumor are not yet known.

Fine-needle aspiration cytology of pleuropulmonary blastoma: case report and review of the literature

This report describes the fine-needle aspiration (FNA) cytology of a case of pleuropulmonary blastoma in a 3-yr-9-mo-old male. Pleuropulmonary blastoma is considered by most authors to be distinct from pulmonary blastoma and is a rare malignant tumor of the intrathoracic cavity. FNA smears were cellular with numerous small ovoid to spindled cells with oval to elliptical nuclei exhibiting finely granular chromatin and inconspicuous nucleoli. The cytoplasm was scant and eosinophilic with indistinct borders. Focal chondroid material and blastema-like cells were noted. The differential diagnosis suggested by the cytologic findings included rhabdomysosarcoma, teratoma, neuroblastoma, malignant mesenchymoma, pleuropulmonary blastoma, and metastatic tumor. To our knowledge, this is the first report of the cytology of this tumor.