Paranuclear blue inclusions in small cell undifferentiated carcinoma: A diagnostically useful finding demonstrated in fine‐needle aspiration biopsy smears

Abstract

In a study of bone marrow aspiration smears, Wittchow et al. (Mod Pathol 1992;5:555-558) described a highly characteristic finding, paranuclear blue inclusions (PBIs), found almost exclusively in cases of metastatic small cell undifferentiated carcinoma (SCUC). PBIs are 1-4 microns, light blue, cytoplasmic inclusions best visualized with Romanowsky-type stains. These inclusions are most easily found indenting the nuclei within clusters of closely opposed tumor cells. In the current study air-dried fine-needle aspiration biopsy (FNAB) smears from 146 primary and metastatic small cell and non-small cell adult and childhood malignancies were reviewed. PBIs were found in 28/32 (88%) of SCUC but were observed in only 4/44 (9%) non-small cell carcinomas, 2/21 (9.5%) lymphomas, 1/8 (12.5%) melanomas, 0/14 sarcomas, and 6/27 (22%) small round cell neoplasms. These results suggest that the presence of PBIs in air-dried FNAB smears of adult neoplasms, while not pathognamonic of SCUC, are a diagnostically useful finding. PBIs may be seen in a variety of different childhood small round cell neoplasms which limits their utility in this setting. The recognition of PBIs is most important to the cytologist who may not have access to ancillary studies, such as immunohistochemistry and electron microscopy.

Paranuclear Blue Inclusions of Small Cell Carcinoma of the Stomach

“…In addition to these cytologic features, some tumor cells had PBIs in the cytoplasm in our case. This finding was identical to that seen in air-dried fine needle aspiration biopsy (FNAB) smears from 146 primary and metastatic small cell and non-small cell malignancies of adulthood and childhood reported by Walker et al 15 They concluded that the presence of PBIs in air-dried FNAB smears of adult neoplasms, while not pathognomonic of small cell carcinoma, was diagnostically useful. Wittchow et al 16 also reported that PBIs were identified in 40 of 47 (85%) cases of metastatic small cell carcinoma on air-dried bone marrow aspirates stained with Wright's stain.…”

Cytomorphologic Characteristics, Differential Diagnosis and Utility During Intraoperative Consultation for Medulloblastoma

“…It is unclear whether PNIs, especially the target inclusions, are the same as paranuclear blue inclusions (PBIs), also known as blue bodies, 20 which are best visualized on air-dried smears stained with Romanowsky-type stains and are commonly observed in small cell undifferentiated carcinomas (SCUCs) of lung. [21][22][23] PBIs are reported not to be demonstrable on alcohol-fixed, H-E-stained cytologic smears. 23 CVs were more frequently seen in the LC/A variant (> 60% of cases).…”

Small Round Cell Tumors of the Abdomen and Thorax

“…21,24,34 PBIs are 1-4-µm, spherical cellular inclusions demonstrated by Romanowsky-stained FNA biopsy material and may represent phagocytosed nuclear/cytoplasmic material (apoptotic bodies). 38 The "intermediate filament buttons," which are present as pale pink, homogeneous, dense, wellcircumscribed round or oval structures in the perinuclear region of cells in neuroendocrine (Merkel cell) carcinoma of the skin, 8 may pose a differential diagnostic problem. However, they can easily be distinguished from PBIs, which invariably occur singly and range from glassy light grey blue to dark blue.…”

“…1 A review of the literature shows that the various cytomorphologic features that could be useful in the diagnosis of SRCT are rosettes and filamentous/fibrillar matrix in neuroblastoma, tubule formation in nephroblastoma, tadpole cells in rhabdomyosarcoma and neuroblastoma, PAS-positive inclusions in Ewing's sarcoma, nuclear grooves in histiocytosis X, noncohesive cells in lymphoma and histiocytosis X, lymphoglandular bodies in NHL, and nuclear molding and PBIs in small cell anaplastic carcinoma. 2,3,12,21,25,31,34,38 Most of these studies were based on either assessment of multiple cytomorphologic characteristics in a specific subtype of SRCT 2,3,24,34 or a single cytomorphologic feature in various SRCTs. 25,38 In the present study an attempt was made to critically assess the role of 12 cytomorphologic features in the diagnosis of specif- The rosettes observed in neuroblastoma and ganglioneuroblastoma have been referred to as "Homer-Wright" rosettes 20,24,34 or pseudorosettes.…”

“…2,3,12,21,25,31,34,38 Most of these studies were based on either assessment of multiple cytomorphologic characteristics in a specific subtype of SRCT 2,3,24,34 or a single cytomorphologic feature in various SRCTs. 25,38 In the present study an attempt was made to critically assess the role of 12 cytomorphologic features in the diagnosis of specif- The rosettes observed in neuroblastoma and ganglioneuroblastoma have been referred to as "Homer-Wright" rosettes 20,24,34 or pseudorosettes. 2,21 When highly organized, these rosettes consist of one or two layers of round, oval or pearshaped cells radially arranged around a central tangle of fibrils, 15,27 but unlike Flexner-Wintersteiner rosettes in retinoblastoma, they do not have a distinct, central lumen with an internal limiting membrane.…”