Pathology of Extramammary
James Paget first described Paget's disease of nipple in 1874.
Fifteen years later Crocker described the first case of extramammary Paget's disease affecting the scrotum and penis.
Dubreuilh described the first case of
vulvar extramammary Paget's disease in 1901.
common site is the anogenital region followed by axilla, eyelid and external
The secondary extramammary Paget disease results from spread of an internal malignancy, most commonly of an anorectal origin or of urothelial origin (bladder, urethra).
A small number of intraepithelial Paget's disease is associated with adnexal adenocarcinoma.
This is referred to as 'pagetoid spread' from the adnexal
The macroscopic appearance ranges from flaking, oozing and maceration to crusted plaque and tumour formation.
The differential diagnosis includes superficial spreading malignant melanoma, Bowen's disease, the epidermal phase of neuroendocrine carcinoma , mycosis fungoides, Toker cells, clear cell papulosis and pagetoid spread of visceral carcinoma.
In superficial spreading melanoma, the tumour cells show prominent nesting along the dermoepidermal junction.
Immunohistochemically, these cells are negative for CAM 5.2, EMA, CEA (these are positive in Paget's disease) and are positive for S100 and HMB45.
No intracellular mucin is seen and there is
no acinar formation in melanoma. In 25% cases S100 expression has been
noted in mammary Paget's disease. In extramammary Paget's disease only
occasional cells show S100 positivity.
Immunohistochemical staining will confirm
the diagnosis (CAM 5.2, EMA, CEA negativity).
However T cell markers will help in establishing the
diagnosis. (CD3, UCHL-1 positive in mycosis fungoides).
In extramammary paget's disease CK20 is negative and GCDFP-15 is positive.
The others stains are negative.
In clear cell papulosis the histological features are similar to toker cell hyperplasia.
cells, these cells have a bland appearance.
In cases of locally invasive extramammary Paget's disease radical surgery with or without adjuvant radiotherapy is advocated.
Primary extramammary Paget's disease, confined to epidermis has a good
Histologically, the most common differential diagnosis includes superficial spreading melanoma and Bowen's disease.
A careful clinicopathological correlation and histological assessment with appropriate histochemical and immunohistochemical staining should allow a confident histological diagnosis of extramammary Paget's disease to be made in most cases.
Intraepidermal cytokeratin 7
expression is not restricted to Paget cells but is also seen in Toker cells
and Merkel cells.
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