Page 802 - Textbook of Pathology, 6th Edition

786 Histologically, it consists of tumour cells arising from the
lower portion of the epidermis and extending downward
into dermis as broad anastomosing bands. The tumour
cells are, however, different from squamous cells. They
are smaller in size, cuboidal in shape and have deeply
basophilic nucleus.

Eccrine hidradenoma. Hidradenoma originates from the
intradermal portion of the eccrine sweat duct. The tumour
may occur anywhere in the body.
Histologically, hidradenoma consists of solid masses and
cords of tumour cells which may have an occasional duct-
like structure containing mucin. The tumour cells are
round to polygonal and may have clear or eosinophilic
cytoplasm.
Eccrine spiradenoma. This is found as a solitary, painful,
circumscribed nodule in the dermis.
Figure 26.28 Pilomatricoma (calcifying epithelioma of Malherbe). Histologically, the tumour consists of lobules which are
The tumour shows islands and lobules within the dermis which are surrounded by a thin capsule. The tumour lobules contain
composed of two types of cells: outer basophilic cells and inner shadow
cells. Areas of calcification are also seen. 2 types of epithelial cells like in the secretory coils of the
eccrine sweat gland. Peripheral cells are small with dark
2. SEBACEOUS ADENOMA. Sebaceous adenoma occurs nuclei, while the centre of lobules contains large cells with
in middle-aged persons, most commonly on the face. pale nuclei. An occasional area may show glandular
structures.
Histologically, it is sharply demarcated from the
surrounding tissue. The tumour is composed of irregular 2. APOCRINE TUMOURS. Apocrine sweat glands may
lobules of incompletely differentiated sebaceous glands. give rise to tumours; the two common examples being
SECTION III
papillary hidradenoma and cylindroma.
3. SEBACEOUS CARCINOMA. Sebaceous carcinoma is a Papillary hidradenoma. Papillary hidradenoma or hidra-
rare tumour that may occur anywhere in the body except denoma papilliferrum is usually located as a small lesion
the palms and soles. Variants of sebaceous carcinoma are commonly in women in the skin of the anogenital area.
carcinoma of the Meibomian glands of the eyelids (page 511)
and carcinoma of the ceruminous glands in the external Histologically, it is a circumscribed tumour in the dermis
meatus. under a normal epidermis. Papillary hidradenoma
represents an adenoma with apocrine differentiation and
Histologically, the tumour is composed of variable-sized
lobules of poorly-differentiated cells containing some containing papillary, tubular and cystic structures. The
sebaceous cells. The tumour cells show marked cytologic tumour cells lining these structures resemble apocrine
Systemic Pathology
atypia such as pleomorphism and hyperchromasia. epithelium with features of decapitation secretions.
Cylindroma. Also called as ‘turban tumour’ due to its
C. Tumours of Sweat Glands common location on the scalp, cylindroma may occur as both

A large number of lesions develop from sweat gland solitary and multiple lesions.
structures, either from apocrine or eccrine glands. These are
more commonly benign but sweat gland carcinoma may also Histologically, the tumour is composed of irregular
occur. islands of tumour cells creating a pattern resembling
jigsaw puzzle. The islands are surrounded by a hyaline
1. ECCRINE TUMOURS. Depending upon the portion of sheath. The tumour cells comprising the islands consist
eccrine sweat gland from which the tumour takes origin, the of 2 types of epithelial cells: peripheral small cells with dark
eccrine tumours are of 3 types: nuclei, and inner large cells with light staining nuclei. Some
i) arising from intraepidermal portion of the duct e.g. eccrine of the islands may contain tubular lumina containing
poroma; amorphous material.
ii) arising from intradermal portion of the duct e.g.
hidradenoma; and 3. SWEAT GLAND CARCINOMA. Rarely, the eccrine and
iii) arising from secretory coils e.g. eccrine spiradenoma. apocrine gland tumours described above may turn
Eccrine poroma. This tumour arises from intraepidermal malignant. All these carcinomas are adenocarcinomas and
portion of the sweat gland duct. The tumour is found more must be distinguished from metastatic adenocarcinoma in
commonly on the sole and hands. the skin.