Images: (dermatopathology
cases)
Spiradenocarcinoma is a rare dermal appendage carcinoma
believed to arise from transformation of a long-standing benign
spiradenoma.
It is an exceedingly rare malignant
neoplasm with ductal differentiation.
The tumour was first
described by Dabska in 1972.
This tumour demonstrates highly malignant biologic behavior
with a high recurrence rate, frequent lymph node metastases , and overall
poor survival.
Many consider it to be an eccrine
neoplasm, and others favour apocrine differentiation.
Clinical presentation:
Usually there is a history of increase in size of the mass,
change in colour or ulceration of the overlying skin. Size of the
lesion ranges between 0.5–15 cm.
Site:
Most lesions usually
arises on the lower extremities and rarely on the trunk.
Microscopic features:
There are two distinct
components, typical spiradenoma and carcinoma with areas of transition ;
Tumour displays monotonous basaloid cells with occasional ductular
differentiation ; Luminal aspect of the tumour cells stain positively
with PAS ; Tumour infiltrates into the deep dermis and extends into the
subcutaneous fat ; Focal areas of necrosis and mononuclear
reactive inflammatory cell infiltration.
Immunohistochemistry:
Tumour cells express cytokeratin ,
epithelial membrane antigen
and p53.
Differential diagnosis:
Merkel cell carcinoma
: Immunohistochemical stains are performed (low molecular weight
cytokeratin, neurofilament, chromogranin, neuron specific enolase and EMA).
In malignant spiradenoma the tumour cells show diffuse cytoplasmic
staining with cytokeratin.
The clinical course is characterised by local recurrences and
metastasis.
The usual sites of metastasis are regional nodes ,bone, lung and liver. |