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Case 12

View the images and select the correct diagnosis from the list below.

Blue cell blues

FNA from a 1.5 cm firm nodule overlying the left parotid gland from an 81-year-old woman with a remote history of basal cell carcinoma:

Image 1 

Image 2 

Image 3 

Image 4 CK20 

Select one of the following:

Case 16 Histology - Poorly differentiated (insular) thyroid carcinoma 


 

You answered: Lymphoma
Sorry, that is INCORRECT 


The correct diagnosis is: Merkel cell carcinoma


CYTOPATHOLOGY:

  • Poorly cohesive population of small blue cells, uniform in appearance. Some clustering may be seen
  • High N/C ratios, rounded nuclei, powdery chromatin (best appreciated on fixed specimens), inconspicuous nucleoli, scant cytoplasm
  • "Blue buttons" (perinuclear cytoplasmic aggregates of intermediate filaments) in cytoplasm, but not specific and is also seen in small cell carcinoma of the lung
  • Immunohistochemistry shows characteristic perinuclear dot-like positivity for CK20, positive for neurofilaments, negative for TTF-1 and CK7 (useful in distinction from small cell carcinoma of lung). It is also negative for LCA (distinction from lymphoma)
  • This is consistent with a diagnosis of Merkel Cell Carcinoma

DISCUSSION:

  • Merkel cell carcinoma is a rare primary neuroendocrine carcinoma of the skin
  • Most occur in the head and neck area or buttocks of elderly patients
  • Clinically, this tumour is nodular with a reddish or violaceous hue, centered in the dermis.
  • They are usually locally agressive and can metastasize
  • Treatment involves wide resection of the primary site and regional lymph node dissection; radiation therapy can be used as an adjunct, and chemotherapy has been employed for metastatic tumours
  • The major differential diagnoses are small cell carcinoma of the lung and malignant lymphoma
  • Merkel cell carcinoma cells are more uniform (with no irregular or spindle-shaped cells), with minimal molding, and show a more dispersed cell pattern when compared to small cell carcinoma of the lung
  • Presence of true tissue aggregates and lack of lymphoglandular bodies aid in differentiating Merkel cell carcinoma from malignant lymphoma
  • Basal cell carcinomas typically show large tight clusters of atypical basaloid cells, with no nuclear molding. Cells characteristically palisade at the periphery on tissue histology

BACK TO IMAGES


HISTOLOGY


REFERENCES:

DeMay RM. The Art & Science of Cytopathology. Chicago: ASCP Press, 1996; 605, 630-1.

Rosai J. Ackerman's Surgical Pathology. Mosby, 8th Edition, 1996; 166-8.

 

You answered: Merkel cell carcinoma

CORRECT!! 

CYTOPATHOLOGY:

  • Poorly cohesive population of small blue cells, uniform in appearance. Some clustering may be seen
  • High N/C ratios, rounded nuclei, powdery chromatin (best appreciated on fixed specimens), inconspicuous nucleoli, scant cytoplasm
  • "Blue buttons" (perinuclear cytoplasmic aggregates of intermediate filaments) in cytoplasm, but not specific and is also seen in small cell carcinoma of the lung
  • Immunohistochemistry shows characteristic perinuclear dot-like positivity for CK20, positive for neurofilaments, negative for TTF-1 and CK7 (useful in distinction from small cell carcinoma of lung). It is also negative for LCA (distinction from lymphoma)
  • This is consistent with a diagnosis of Merkel Cell Carcinoma

DISCUSSION:

  • Merkel cell carcinoma is a rare primary neuroendocrine carcinoma of the skin
  • Most occur in the head and neck area or buttocks of elderly patients
  • Clinically, this tumour is nodular with a reddish or violaceous hue, centered in the dermis.
  • They are usually locally agressive and can metastasize
  • Treatment involves wide resection of the primary site and regional lymph node dissection; radiation therapy can be used as an adjunct, and chemotherapy has been employed for metastatic tumours
  • The major differential diagnoses are small cell carcinoma of the lung and malignant lymphoma
  • Merkel cell carcinoma cells are more uniform (with no irregular or spindle-shaped cells), with minimal molding, and show a more dispersed cell pattern when compared to small cell carcinoma of the lung
  • Presence of true tissue aggregates and lack of lymphoglandular bodies aid in differentiating Merkel cell carcinoma from malignant lymphoma
  • Basal cell carcinomas typically show large tight clusters of atypical basaloid cells, with no nuclear molding. Cells characteristically palisade at the periphery on tissue histology

BACK TO IMAGES


HISTOLOGY


REFERENCES:

DeMay RM. The Art & Science of Cytopathology. Chicago: ASCP Press, 1996; 605, 630-1.

Rosai J. Ackerman's Surgical Pathology. Mosby, 8th Edition, 1996; 166-8.


You answered: Basal cell carcinoma
Sorry, that is INCORRECT 

The correct diagnosis is: Merkel cell carcinoma

CYTOPATHOLOGY:

  • Poorly cohesive population of small blue cells, uniform in appearance. Some clustering may be seen
  • High N/C ratios, rounded nuclei, powdery chromatin (best appreciated on fixed specimens), inconspicuous nucleoli, scant cytoplasm
  • "Blue buttons" (perinuclear cytoplasmic aggregates of intermediate filaments) in cytoplasm, but not specific and is also seen in small cell carcinoma of the lung
  • Immunohistochemistry shows characteristic perinuclear dot-like positivity for CK20, positive for neurofilaments, negative for TTF-1 and CK7 (useful in distinction from small cell carcinoma of lung). It is also negative for LCA (distinction from lymphoma)
  • This is consistent with a diagnosis of Merkel Cell Carcinoma

DISCUSSION:

  • Merkel cell carcinoma is a rare primary neuroendocrine carcinoma of the skin
  • Most occur in the head and neck area or buttocks of elderly patients
  • Clinically, this tumour is nodular with a reddish or violaceous hue, centered in the dermis.
  • They are usually locally agressive and can metastasize
  • Treatment involves wide resection of the primary site and regional lymph node dissection; radiation therapy can be used as an adjunct, and chemotherapy has been employed for metastatic tumours
  • The major differential diagnoses are small cell carcinoma of the lung and malignant lymphoma
  • Merkel cell carcinoma cells are more uniform (with no irregular or spindle-shaped cells), with minimal molding, and show a more dispersed cell pattern when compared to small cell carcinoma of the lung
  • Presence of true tissue aggregates and lack of lymphoglandular bodies aid in differentiating Merkel cell carcinoma from malignant lymphoma
  • Basal cell carcinomas typically show large tight clusters of atypical basaloid cells, with no nuclear molding. Cells characteristically palisade at the periphery on tissue histology

BACK TO IMAGES


HISTOLOGY


REFERENCES:

DeMay RM. The Art & Science of Cytopathology. Chicago: ASCP Press, 1996; 605, 630-1.

Rosai J. Ackerman's Surgical Pathology. Mosby, 8th Edition, 1996; 166-8.

Case 12 Histology - Merkel Cell Carcinoma

 


 

From the Cytopathology files of the BC Cancer Agency
Submitted by: Carol Lee, MD and Tom Thomson, MD

SOURCE: Case 12 ( )
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