Combined use of EUS-guided FNA and immunocytochemical stains discloses metastatic and unusual diseases in the evaluation of mediastinal lymphadenopathy of unknown etiology

Abstract

Purpose: Mediastinal lymphadenopathy (ML) is a cause for concern, especially in patients with previous malignancy. We report our experience with the use of endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) with immunocytochemical stains in patients being evaluated for ML.

Methods: Retrospective analysis of patients with ML of unknown origin who underwent EUS-FNA. On-site evaluation was performed by experienced cytologist, and special immunocytochemical stains were requested as indicated.

Results: A total of 116 patients were included, and a total of 136 mediastinal LN were sampled. Prior malignancy was present in 45%. The most common site of examined lymph node (LN) were subcarinal (76%, 103 LN). The median long and short axis diameters were 28 mm and 13 mm, respectively. FNA was read on-site as malignant, 21 (16%); benign, 100 (76.9%); suspicious, six (4%); atypical, 3 (2%); and inadequate sample, six (4%). Sixty-four LN were deferred for additional studies; 22 for immunocytochemical and 26 for Gimesa (GMS) stain and 21 for flow cytometry. Final FNA read was malignant in 28 (21%), benign in 103 (76%), suspicious in three (2%), and atypical in two (1%). Metastatic malignancies disclosed included Hodgkin's and Non-Hodgkin's lymphoma, melanoma, hepatoma, breast, lung, colon, renal, endometrial, Fallopian tube, and unknown carcinoma. The sensitivity, specificity, and accuracy of the final FNA read to predict malignancy were 100%.

Conclusion: EUS-guided FNA with additional ancillary studies is useful in disclosing metastatic ML from a variety of neoplasms. Due to its safety and accuracy profile, it should be considered the test of choice in evaluating abnormal ML in appropriately selected patients.

Keywords: Endoscopic ultrasound; fine needle aspiration; immunostains; lung cancer; metastatic disease.

Figure 1

(a) Aspirate smear, Diff-Quik stain, power, ×20 showing pleomorphic malignant-appearing cells, with large nuclei and nucleoli. (b) Cell block, H and E stain, power ×10, showing clumps of atypical cells. (c) Cell block, Estrogen receptor stain, showing the strong nuclear stain, some cells with intracytoplasmic mucin consistent with breast cancer, ×40

Figure 2

Diff-Quik smear: Metastatic carcinoma, renal cell type showing clumps of malignant-appearing cells with abundant clear cytoplasm, ×20. Atypical cells are immunoreactive for CD10, vimentin, and broad-spectrum cytokeratin, RCC. Inset: Higher magnification showing clear, vacuolated cytoplasm with large nuclei, prominent nucleoli typical of RCC (cell block, ×40)

Figure 3

Left hilar node, cell block, immunohistochemical stain for vimentin ×20. The atypical cells described in Figure 2 stain positively with vimentin supporting the diagnosis of metastatic Renal Cell Carcinoma

Figure 4

Colon Adenocarcinoma. (a) Aspirate smear, Diff-Quik stain, power, ×20 with large adherent groups of pleomorphic cells with increased nucleus to cytoplasm ratio. (b) Cell block, Mucicarmine stain indicating presence of mucin in the atypical cells which appear arranged in glandular structures, power, ×40

Figure 5

Melanoma (a) Cell block, S-100 stain showing a positive (brown) nuclear and cytoplasmic staining, ×10. (b) Aspirate smear, Diff-Quik stain, ×20 with highly pleomorphic cells, some binucleated with prominent nucleoli. (c) Cell block, higher magnification showing characteristic prominent cherry red nucleoli