Epidermal growth factor receptor mutations correlated with adenocarcinoma with bronchioloalveolar pattern, (5,16) terminal respiratory unit adenocarcinoma, (21) papillary and micropapillary adenocarcinoma subtypes, (13) micropapillary pattern and hobnail cell
type of adenocarcinoma, (22) and absence of solid growth pattern.
Correlation between morphology and EGFR mutations in lung adenocarcinomas Significance of the micropapillary pattern and the hobnail cell
32-34) A micropapillary and hobnail cell
type has also been reported to be associated with EGFR mutations.
Concerning histopathology, a bronchioloalveolar carcinoma (BAC) histologic feature and well-differentiated to moderately differentiated grades were earlier reported to predict responsiveness to the EGFR tyrosine kinase (TK) inhibitor and the presence of EGFR mutations (33,34) The finding that the hobnail cell
type and a micropapillary morphology can predict a higher incidence of EGFR mutations in lung adenocarcinomas has been reported more recently.
Papillary and tubulocystic patterns should be found with hobnail cells
lining the cysts and mononuclear inflammatory infiltrate.
Nephrogenic adenoma of the urinary bladder is defined as a metaplastic change in the urinary bladder with papillary or cryptic structures which are composed of small hollow tubules similar to mesonephric tubules, which are usually lined by a single layer of bland cuboidal or hobnail cells
, surrounding eosinophilic or basophilic secretions .
The presence of hobnail cells
and extracellular mucin are more typical of clear cell carcinoma of the ovary, while a solid and tubular growth pattern with bland cells and a prominent vascular network raises the possibility of a metastasis of clear cell RCC.
F, Collecting duct carcinoma example with hobnail cells
, enlarged irregular nuclei, and prominent nucleoli, arranged in infiltrating nests with stromal desmoplasia (hematoxylin-eosin, original magnification X200 [A, B, C, E, and F]; original magnification X200 [D]).
b) microscopic characteristics; pattern, small tubules and cysts which resemble renal tubules; hobnail cells
are present; mitosis is absent; cytoplasm is scant and eosinophilic; the nuclei are bland;
F: tubules lined by hobnail cells
(arrows) showing focal atypias due to a degenerative process (H&E, 200x).
Cellular atypia is manifested as enlarged, hobnail cells
with vacuolated or microvesicular cytoplasm (Figure 2, A through C).
100,295,296) Moreover, specific features of the different subtypes of cervical adenocarcinoma in the differential diagnosis are also helpful, including: (1) cystic and papillary patterns and clear and hobnail cells
in clear cell carcinoma (296); (2) numerous mitoses, cells with mucinous differentiation, and occasionally associated AIS or squamous dysplasia in usual-type endocervical adenocarcinoma (162,165,166); and (3) cells with cilia, mucinous differentiation, and associated tuboendometrioid metaplasia in endometrioid-type endocervical adenocarcinoma.