Metastatic tumors

• Colorectal carcinoma
  • Tall (columnar), dark (hyperchromatic) cells and necrosis
• Breast carcinoma and gastric carcinoma
  • Signet ring cells
• Prostate carcinoma
  • Microacini
  • Prominent nucleoli
  • Immunoreactive for Prostatic Specific Antigen and Prostatic Acid Phosphatase
• Well-differentiated neuroendocrine tumors
  • Eccentrically placed nuclei
  • ‘salt-and-pepper’ chromatin pattern
  • Abundant granular cytoplasm
  • Single cells, loosely cohesive clusters and rosettes
  • Immunoreactive for neuroendocrine markers
• Small cell carcinoma
  • Isolated and loosely cohesive cells
  • Nuclear molding
  • Hyperchromatic nuclei with finely granular chromatin and incospicuous nucleoli
  • Round, polygonal or spindle cells
• Squamous cell carcinoma
  • Small, dark nuclei
  • Abundant cytoplasm with a hard, glassy appearance (orange with Papanicolaou stain
    and gray with Romanowsky-type stain) in well-differentiated tumors
• Sarcoma
  • Spindle cells (differential diagnosis: metastatic sarcomatoid carcinoma)
• Malignant melanoma
  • Abundant, sometimes pigmented, cytoplasm
  • Intranuclear pseudoinclusions and macronucleoli
  • Single cell pattern
  • Finely granular melanin pigment
  • Immunoreactive for S-100 and HMB-45
• Lymphoma