title: Mixed squamous cell and glandular papilloma of the lung resembling early adenocarcinoma: A case report.
abstract: BACKGROUND
  An extremely rare case of mixed squamous cell and glandular papilloma of the lung is reported. The correlation between the radiological and the pathological features as well as the clinical pitfall in making a diagnosis is discussed.
  
  
  METHODS
  An asymptomatic 68-year-old female with a cigarette smoking habit presented with a small nodule in her peripheral lung. A wedge resection was performed though it failed on-site diagnosis which was instead obtained following pathological scrutiny. The postsurgical course was excellent with no recurrence of disease.
  
  
  CONCLUSIONS
  A small ground glass nodule gradually enlarged and transformed to a partially solid nodule a year and a half later. This transformation falsely made us suspect an early adenocarcinoma development. Eventually, the extremely rare subtype of pulmonary papilloma, with biphasic glandular and squamous cells, had been demonstrated to obstruct the peripheral bronchiole; and the adjoining alveoli had filled with a large volume of mucus. These pathological features seemed to have constituted the inner solid portion and the marginal ground glass portion respectively in the CT images, mimicking invasive lepidic adenocarcinoma.
  
  
  CONCLUSIONS
  Both pre- and intra-operative diagnoses are difficult mainly because of the rareness of the disease, however, mixed squamous cell and glandular papilloma may be considered in case the presence of primary adenocarcinoma is not validated.
authors.affiliation: Department of Thoracic Surgery, Miyagi Cancer Center, 47-1 Nodayama, Medeshima-Shiote, Natori, Miyagi, 981-1293, Japan.
authors.forename: Jiro
authors.initials: J
authors.lastname: Abe
authors.affiliation: Department of Pathology, Miyagi Cancer Center, 47-1 Nodayama, Medeshima-Shiote, Natori, Miyagi, 981-1293, Japan.
authors.forename: Shigemi
authors.initials: S
authors.lastname: Ito
authors.affiliation: Department of Thoracic Surgery, Miyagi Cancer Center, 47-1 Nodayama, Medeshima-Shiote, Natori, Miyagi, 981-1293, Japan.
authors.forename: Satomi
authors.initials: S
authors.lastname: Takahashi
authors.affiliation: Department of Pathology, Miyagi Cancer Center, 47-1 Nodayama, Medeshima-Shiote, Natori, Miyagi, 981-1293, Japan.
authors.forename: Ikuro
authors.initials: I
authors.lastname: Sato
authors.affiliation: Department of Thoracic Surgery, Miyagi Cancer Center, 47-1 Nodayama, Medeshima-Shiote, Natori, Miyagi, 981-1293, Japan; Department of Thoracic Surgery, Tohoku University Graduate School of Medicine, 4-1 Seiryo-cho, Aoba-ward, Sendai, Miyagi, 980-8575, Japan.
authors.forename: Ryota
authors.initials: R
authors.lastname: Tanaka
authors.affiliation: Department of Thoracic Surgery, Miyagi Cancer Center, 47-1 Nodayama, Medeshima-Shiote, Natori, Miyagi, 981-1293, Japan; Department of Thoracic Surgery, Tohoku University Graduate School of Medicine, 4-1 Seiryo-cho, Aoba-ward, Sendai, Miyagi, 980-8575, Japan.
authors.forename: Taku
authors.initials: T
authors.lastname: Sato
authors.affiliation: Department of Thoracic Surgery, Miyagi Cancer Center, 47-1 Nodayama, Medeshima-Shiote, Natori, Miyagi, 981-1293, Japan; Department of Thoracic Surgery, Tohoku University Graduate School of Medicine, 4-1 Seiryo-cho, Aoba-ward, Sendai, Miyagi, 980-8575, Japan.
authors.forename: Toshimasa
authors.initials: T
authors.lastname: Okazaki
keywords: 18F-fluorodeoxyglucose positron emission tomography; Adenocarcinoma in situ; Case report; FDG-PET; Ground glass nodule; HPVs; Invasive lepidic adenocarcinoma; MSCGP; Pulmonary papilloma; SUV; human papilloma viruses; mixed squamous cell and glandular papilloma; standardized uptake value