Case 14

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

"It ain't no smyelin' matter"

FNAB of a painless parotid lesion with a recent rapid increase in size, present for approximately eight years in a 40-year-old man:

Select one of the following:

A) Pleomorphic Adenoma

You answered: Pleomorphic Adenoma
Sorry, that is INCORRECT

The correct answer is: Schwannoma

Cytopathology:

The smears reveal loose clusters of cells in a myxoid background
The cells are oval and spindle-shaped; some have slightly bent nuclei
There is moderate variation in nuclear size and shape. Some nuclear palisading is noted

Discussion:

Schwannoma, also known as neurilemoma, is a benign, encapsulated tumour of Schwann cells found throughout the peripheral nervous system. They are commonly found in the head and neck region
Aspiration biopsy is often unusually painful
Treatment is simple surgical excision
Tumour cells strongly express S100 protein and vimentin
Histologically, schwannomas often have cellular and less cellular areas referred to as Antoni A and Antoni B areas respectively
- Antoni A areas may contain regions of bundles of spindle shaped Schwann cells with palisading nuclei surrounding a central fibrillar core known as Verocay bodies (not present in this case)
- Antoni B areas contain few randomly arranged Schwann cells within loose myxoid stroma
Cytologic differential diagnosis:
- Pleomorphic adenoma may be suggested by the myxoid stroma and spindle cells. Confident diagnosis of PA requires identification of epithelial and/or myoepithelial cells in a metachromatic, usually fibrillar, stroma
- Nodular fasciitis may have spindle cells and myxoid stroma. A history of rapid growth is usually noted. Unlike Schwannoma the bland appearing spindle cells have wispy bipolar cytoplasmic processes and tend not to form Antoni A and B areas. Often a background of chronic inflammation is present
- The spindle cell variant of myoepithelioma may mimic Schwannoma but does not usually have a significant stromal component.

Back to images

Histology

References:

Demay RM. The Art & Science of Cytopathology: Chicago: ASCP Press, 1996; 585-587, 669-673.

Faquin WC, Powers CN. Cytologic Evaluation of Salivary Gland Aspirates: A Case-Based Approach with Histologic Correlation. American Society of Cytopathology 53rd Annual Scientific Meeting. San Diego, CA, November 4-9, 2005.

Gray W, McKee GT. Diagnostic Cytopathology. 2nd Edition. Elsevier Science Limited 2003; 311, 884-896.

B) Schwannoma

You answered: Schwannoma

CORRECT!!

Cytopathology:

The smears reveal loose clusters of cells in a myxoid background
The cells are oval and spindle-shaped; some have slightly bent nuclei
There is moderate variation in nuclear size and shape. Some nuclear palisading is noted

Discussion:

Schwannoma, also known as neurilemoma, is a benign, encapsulated tumour of Schwann cells found throughout the peripheral nervous system. They are commonly found in the head and neck region
Aspiration biopsy is often unusually painful
Treatment is simple surgical excision
Tumour cells strongly express S100 protein and vimentin
Histologically, schwannomas often have cellular and less cellular areas referred to as Antoni A and Antoni B areas respectively
- Antoni A areas may contain regions of bundles of spindle shaped Schwann cells with palisading nuclei surrounding a central fibrillar core known as Verocay bodies (not present in this case)
- Antoni B areas contain few randomly arranged Schwann cells within loose myxoid stroma
Cytologic differential diagnosis:
- Pleomorphic adenoma may be suggested by the myxoid stroma and spindle cells. Confident diagnosis of PA requires identification of epithelial and/or myoepithelial cells in a metachromatic, usually fibrillar, stroma
- Nodular fasciitis may have spindle cells and myxoid stroma. A history of rapid growth is usually noted. Unlike Schwannoma the bland appearing spindle cells have wispy bipolar cytoplasmic processes and tend not to form Antoni A and B areas. Often a background of chronic inflammation is present
- The spindle cell variant of myoepithelioma may mimic Schwannoma but does not usually have a significant stromal component

Back to Images

Histology

References:

Demay RM. The Art & Science of Cytopathology: Chicago: ASCP Press, 1996; 585-587, 669-673.

Gray W, McKee GT. Diagnostic Cytopathology. 2nd Edition. Elsevier Science Limited 2003; 311, 884-896.

C) Nodular Fasciitis

You answered: Nodular Fasciitis
Sorry, that is INCORRECT

The correct answer is: Schwannoma

Cytopathology:

The smears reveal loose clusters of cells in a myxoid background
The cells are oval and spindle-shaped; some have slightly bent nuclei
There is moderate variation in nuclear size and shape. Some nuclear palisading is noted

Discussion:

Schwannoma, also known as neurilemoma, is a benign, encapsulated tumour of Schwann cells found throughout the peripheral nervous system. They are commonly found in the head and neck region
Aspiration biopsy is often unusually painful
Treatment is simple surgical excision
Tumour cells strongly express S100 protein and vimentin
Histologically, Schwannomas often have cellular and less cellular areas referred to as Antoni A and Antoni B areas respectively
- Antoni A areas may contain regions of bundles of spindle shaped Schwann cells with palisading nuclei surrounding a central fibrillar core known as Verocay bodies (not present in this case)
- Antoni B areas contain few randomly arranged Schwann cells within loose myxoid stroma
Cytologic differential diagnosis:
- Pleomorphic adenoma may be suggested by the myxoid stroma and spindle cells. Confident diagnosis of PA requires identification of epithelial and/or myoepithelial cells in a metachromatic, usually fibrillar, stroma
- Nodular fasciitis may have spindle cells and myxoid stroma. A history of rapid growth is usually noted. Unlike Schwannoma the bland appearing spindle cells have wispy bipolar cytoplasmic processes and tend not to form Antoni A and B areas. Often a background of chronic inflammation is present
- The spindle cell variant of myoepithelioma may mimic Schwannoma but does not usually have a significant stromal component

Back to Images

Histology

References:

Demay RM. The Art & Science of Cytopathology: Chicago: ASCP Press, 1996; 585-587, 669-673.

Gray W, McKee GT. Diagnostic Cytopathology. 2nd Edition. Elsevier Science Limited 2003; 311, 884-896.

D) Myoepithelioma

You answered: Myoepithelioma
Sorry, that is INCORRECT

The correct answer is: Schwannoma

Cytopathology:

The smears reveal loose clusters of cells in a myxoid background
The cells are oval and spindle-shaped; some have slightly bent nuclei
There is moderate variation in nuclear size and shape. Some nuclear palisading is noted

Discussion:

Schwannoma, also known as neurilemoma, is a benign, encapsulated tumour of Schwann cells found throughout the peripheral nervous system. They are commonly found in the head and neck region
Aspiration biopsy is often unusually painful
Treatment is simple surgical excision
Tumour cells strongly express S100 protein and vimentin
Histologically, schwannomas often have cellular and less cellular areas referred to as Antoni A and Antoni B areas respectively
- Antoni A areas may contain regions of bundles of spindle shaped Schwann cells with palisading nuclei surrounding a central fibrillar core known as Verocay bodies (not present in this case)
- Antoni B areas contain few randomly arranged Schwann cells within loose myxoid stroma
Cytologic differential diagnosis:
- Pleomorphic adenoma may be suggested by the myxoid stroma and spindle cells. Confident diagnosis of PA requires identification of epithelial and/or myoepithelial cells in a metachromatic, usually fibrillar, stroma
- Nodular fasciitis may have spindle cells and myxoid stroma. A history of rapid growth is usually noted. Unlike Schwannoma the bland appearing spindle cells have wispy bipolar cytoplasmic processes and tend not to form Antoni A and B areas. Often a background of chronic inflammation is present
- The spindle cell variant of myoepithelioma may mimic Schwannoma but does not usually have a significant stromal component

Back to Images

Histology

References:

Demay RM. The Art & Science of Cytopathology: Chicago: ASCP Press, 1996; 585-587, 669-673.

Gray W, McKee GT. Diagnostic Cytopathology. 2nd Edition. Elsevier Science Limited 2003; 311, 884-896.

Histology

From the Cytopathology files of BC Cancer

Submitted by: Amanda Reith, BSc; edited by Brenda Smith, BSc and Tom Thomson, MD