| [Syringoid Eccrine Carcinoma ; Sclerosing Sweat gland Carcinoma ; Eccrine
Syringomatous Carcinoma]
A rare type of locally
aggressive
sweat gland carcinoma which was originally described as a
basal cell carcinoma with eccrine differentiation (eccrine epithelioma)
by
Freeman et al in 1969
. This
tumour was later reported as eccrine syringomatous carcinoma by other
authors.
Tumour presents as a
plaque or firm nodule on the scalp, extremities or trunk of middle aged
adults.
Aggressive local
recurrence is common. Distant metastasis is usually rare.
Microscopic features:
Image1 ;
Image2 ;
Image3
Infiltrating tumour located in the dermis ; May invade into the
subcutaneous fat and muscle ; Composed of solid nests , cords and small
tubules lined by basaloid cells ; Tubules may contain PAS positive,
diastase resistant, alcian blue positive material ; Some ducts
demonstrate tail-like extension resembling syringoma. This feature is
also present in microcystic
adnexal carcinoma(MAC).
; Clear cell variant has been reported ; Backround stroma is usually
desmoplastic in nature ; Perineural invasion is often identified ;
Cytological atypia is not prominent ; Mitotic activity is not
significant.
Differential diagnosis :
Syringoma, basal cell carcinoma,
microcystic adnexal
carcinoma
,
adenoid cystic carcinoma,
metastatic carcinoma. Syringomatous carcinoma is distinguished from MAC
on the basis of a lack of follicular (keratocyst, hair germ, matricial) or
sebaceous differentiation. According to some authors Syringomatous
carcinoma is part of the spectrum of MAC.
|