Lung Mass: Diagnosis

Lung Mass: Diagnosis
Pulmonary adenocarcinoma image is most often seen in a peripheral location and may show “puckering” image or indentation of the pleural surface if the visceral pleura is involved. (Courtesy G. Gray, MD.)
The majority of cases of well- to moderately differentiated adenocarcinoma characteristically demonstrate obvious gland formation image, distinguishing this type of cancer from squamous cell carcinoma.
SURGICAL/CLINICAL CONSIDERATIONS
Goal of Consultation
  • Provide or confirm diagnosis on lung mass
  • If malignant, margin of specimen should be evaluated
Change in Patient Management
  • If diagnosis of malignancy is made, additional surgery may be performed to achieve tumor-free margins &/or stage tumor
Clinical Setting
  • Small masses (< 1 cm) are frequently detected by imaging
    • Excision is often necessary for diagnosis
      • ˜ 70% are primary lung malignancies
      • ˜ 10% are metastases to lung
      • ˜ 20% are nonmalignant lesions
  • Large masses (> 2 cm) are generally diagnosed prior to surgery through transbronchial or CT-guided biopsy and do not necessarily require confirmation
    • Adenocarcinomas with pure lepidic pattern on biopsy will likely need to be fully evaluated on permanent section to exclude invasive component
SPECIMEN EVALUATION
Gross
  • Masses may be excised by wedge resection, lobectomy, or pneumonectomy
  • Pleural surface should be carefully inspected
    • Adhesions: May be associated with inflammatory changes or invasion of tumor through pleura
    • Puckering: Usually due to retraction by carcinoma that has invaded into, but not through, pleura
      • Pleural invasion is used for staging and is important prognostic factor
    • Lymphangitic spread: White color of pleural lymphatics indicating extensive lymphovascular invasion
  • Specimen is palpated to identify site of all masses and relationship to any pleural changes
    • Pleura will not move freely over carcinomas that have invaded into pleura
  • Specimen is completely serially sectioned to reveal any palpated mass and smaller &/or less firm masses
    • Any areas of possible pleural involvement should be preserved for later evaluation by permanent sections
  • Size and location of all masses are recorded
  • Distance of lesions to parenchymal margins and bronchial margins is recorded
Frozen Section
  • Representative section of mass is frozen
  • If lesion has “cheesy” or necrotic surface, touch preps may be indicated in lieu of frozen sections to avoid potential contamination of cryostat with infectious organism (e.g., Mycobacterium tuberculosis)
  • If surgical margin is nearby, 1 section may be able to demonstrate both diagnosis and margin
Cytology
  • Touch preps of cut surface of mass lesion may be helpful if conservation of tumor tissue for permanent section is necessary or if infectious granulomatous disease is possible
    • Suspicion for lymphoma generally requires fresh tissue to be sent for additional ancillary testing (e.g., flow cytometry, cytogenetics)
    • Presence of granulomas on touch prep from small necrotic mass suggests infectious etiology, and subsequent frozen section may not be indicated
MOST COMMON DIAGNOSES
Adenocarcinoma: Conventional/Nonlepidic Pattern
  • Most common diagnosis overall
  • Morphology (glandular vs. solid) depends heavily on degree of differentiation
  • Desmoplastic stroma or extensive chronic inflammatory response is often seen
  • Morphologic variants (e.g., papillary, micropapillary, and solid with mucin production) are occasionally seen
Adenocarcinoma In Situ
  • Synonymous term with pure lepidic pattern adenocarcinoma
    • Many cancers previously termed bronchioloalveolar would be in this category
  • By definition, mass must be < 3 cm to make this diagnosis
  • Often presents as ground-glass opacity on chest x-ray
  • Grossly forms ill-defined firmer area of lung parenchyma
    • Lymphomas and focal pneumonia can have similar gross appearance
  • This diagnosis should not be rendered without histologic evaluation of entire mass on permanent section to exclude invasion
  • Multiple lesions may be present
Metastatic Carcinoma/Sarcoma
  • Previous documented history of malignancy (e.g., colonic adenocarcinoma, osteosarcoma) is invaluable
  • Metastatic disease to lung is more likely to present as multiple nodules rather than as single nodule
  • Distinction between primary malignancy and metastasis may not always be possible at time of frozen section
Squamous Cell Carcinoma
  • More likely to be centrally located than adenocarcinomas
  • May have gritty cut surface depending on amount of keratin production by tumor
Carcinoid
  • Most cases occur centrally, especially in endobronchial location
    • Often bilobed with endobronchial component and component in bronchial wall
  • Patients are generally younger than typical patient with lung carcinoma
Small Cell Carcinoma
  • Rarely resected as many have metastasized at time of diagnosis
Non-Small Cell Carcinoma, Not Further Classified
  • Acceptable diagnosis in setting of poorly differentiated large cell carcinoma for which thorough sampling &/or immunohistochemistry is necessary for precise classification
Chondroid Hamartoma
  • Generally small and well circumscribed
  • Typically demonstrates blue-gray glassy cut surface due to cartilaginous composition
Granuloma
  • Usually small (< 1 cm) and round; may be multiple
  • Cut surface varies from soft/necrotic to solid/firm to bony/rock hard
  • Granulomas with necrotic/“cheesy” cut surface are more likely to contain fungi (e.g., Histoplasma) or mycobacteria, among other organisms
  • Tissue should be kept sterile and sent for cultures
    • Frozen sections should be avoided to minimize exposure of personnel to infectious agents and contamination of cryostat
Other Nonneoplastic Inflammatory Changes
  • Entities known to present with nodularities include abscess, organizing pneumonia (round pneumonia), granulomatosis with polyangiitis (Wegener granulomatosis), and hypersensitivity pneumonitis
Atypical Adenomatous Hyperplasia
  • Incidental finding that should not create grossly identifiable mass lesion
  • Size: < 5 mm in diameter
Lymphoma
  • Most common are extranodal marginal zone lymphoma (lymphoma of mucosa-associated lymphoid tissue) and diffuse large B-cell lymphoma
  • Tissue should be taken for special studies (e.g., special fixatives, frozen tissue, tissue for flow cytometry)
Intraparenchymal Lymph Node
  • Often located near pleura and grossly black due to anthracotic pigment
REPORTING
Frozen Section
  • Diagnosis of malignant or benign lesion is usually sufficient for intraoperative management
    • Subtypes of carcinoma are not critical intraoperatively
    • If patient has known primary carcinoma elsewhere, surgeon may want opinion as to whether lesion is likely metastasis or primary carcinoma
      • Distinction may not be possible on frozen section
PITFALLS
Lepidic Pattern Adenocarcinoma vs. Nonneoplastic Inflammatory Changes
  • Primary distinction is by the more pronounced nuclear atypia in adenocarcinomas
  • Adenocarcinoma is more likely to show nuclear inclusions
  • Carcinomas generally have thicker septal walls
Metastatic Carcinoma vs. Primary Lung Carcinoma
  • Important to know history of any prior malignant tumors and histologic type
  • May not be possible to make this distinction on frozen section
Lymphoma vs. Intraparenchymal Lymph Node
  • Lymphoma generally is larger with irregular border and lacks tan, fleshy cut surface of lymph node
  • Histologic architectural hallmarks of lymph node (capsule, subcapsular sinus, etc.) should be sought if tissue is frozen
  • Pure cytologic evaluation (i.e., touch prep only) may be of limited use depending on grade of lymphoma
Necrotic Malignancy vs. Necrotic Granuloma
  • Distinction can be challenging if lesion is totally necrotic
  • Malignancies (both primary and metastatic) are generally larger than infectious lesions
  • Granuloma formation on touch prep or frozen section suggests infectious origin, but rare exceptions exist
  • Tissue should be taken for cultures if infectious process is suspected
RELATED REFERENCES
1. Xu X et al: The accuracy of frozen section diagnosis of pulmonary nodules: evaluation of inflation method during intraoperative pathology consultation with cryosection. J Thorac Oncol. 5(1):39-44, 2010
2. Gupta R et al: What can we learn from the errors in the frozen section diagnosis of pulmonary carcinoid tumors? An evidence-based approach. Hum Pathol. 40(1):1-9, 2009
3. Herbst J et al: Evidence-based criteria to help distinguish metastatic breast cancer from primary lung adenocarcinoma on thoracic frozen section. Am J Clin Pathol. 131(1):122-8, 2009
4. Gupta R et al: Lessons learned from mistakes and deferrals in the frozen section diagnosis of bronchioloalveolar carcinoma and well-differentiated pulmonary adenocarcinoma: an evidence-based pathology approach. Am J Clin Pathol. 130(1):11-20; quiz 146, 2008
5. Myung JK et al: A simple inflation method for frozen section diagnosis of minute precancerous lesions of the lung. Lung Cancer. 59(2):198-202, 2008

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Jul 7, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Lung Mass: Diagnosis

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