Sweat Gland Lesions Flashcards
Hidrocystoma
- Uncommon benign adenomatous cystic proliferation derived from apocrine glands
- These lesions are usually small (< 2 cm), on face of older adults
- Despite its apocrine derivation, rare at sites rich in normal apocrine glands (groin, axilla, anogenital region, eyelids [Moll’s glands], ears [ceruminous glands])
- Usually solitary, but multiple lesions have been documented
- Solitary lesions are not familial, but multiple apocrine hidrocystomas are a feature of ectodermal dysplasia and focal dermal hypoplasia (Goltz syndrome)
Micro:
* Large unilocular or multilocular cystic space within dermis
* Fibrous pseudocapsule is often present
* Typically, cystic spaces are lined by double layer of epithelial cells: an outer layer of flattened vacuolated myoepithelial cells and an inner layer of tall columnar cells
* Decapitation secretion is usually present
IHC:
* AE1 / AE3
* PAS-positive, diastase resistant granules may be evident in the cytoplasm of the inner lining cells
* Myoepithelial layer: smooth muscle actin (SMA), p63
HER2:
Hidradenoma
- Benign dermal nodule of eccrine gland derivation
- Also known as nodular hidradenoma, eccrine acrospiroma, clear cell hidradenoma, eccrine sweat gland adenoma and solid cystic hidradenoma
- Recurrence rate of 12% if not completely excised
- Solitary well circumscribed dermal nodule
Micro:
* Well circumscribed but unencapsulated, lobulated / cystic mass with variably sized nests and nodules of epithelial cells within the upper or mid dermis
* Typically with no overlying connection to the epidermis
* Shows both solid and cystic components
* Solid portion composed of 2 types of cells: polyhedral cells with basophilic cytoplasm and glycogen containing clear cells with eccentric round nucleus
* Cystic areas secondary to degeneration of tumor cells
* Tubular lumina are lined by cuboidal or columnar secretory cells
* Fibrovascular, collagenous or hyalinized stroma
Eccrine Poroma
- Benign glandular adnexal tumor that usually originates from cells of the outer layer of the acrosyringium and terminal eccrine duct
- Single, slow growing, asymptomatic, well circumscribed, smooth, skin colored to red, slightly scaly papule or nodule
- Most commonly on palms and sole or sides of the foot
Micro:
* Well circumscribed
* Replaces the epidermis and extends into the dermis in broad anastomosing bands
* Poroma cells are monomorphic, small, cuboidal with basophilic round nuclei, inconspicuous nucleoli and compact eosinophilic cytoplasm
* Sharp demarcation present between the normal keratinocytes and poroma cells
* Devoid of peripheral palisading
* Ductal lumina with single row of luminal cells covered by eosinophilic lining or cystic spaces devoid of any formal lining
IHC:
CK5/6, CK7, EMA, CEA, CAM5.2, CD117, diastase PAS
Syringoma
- Benign adnexal neoplasm of sweat gland (eccrine) origin
- Most common clinical presentation on lower eyelids of women
- Appears to derive from sweat duct ridge
- Malignant counterpart can be termed syringomatous carcinoma / sweat gland carcinoma
- Benign, nonprogressive lesions but can be cosmetically bothersome if multiple
- Recurrence, scarring and dyspigmentation after treatment
Increased incidence:
* Japanese women
* Down
* Ehlers-Danlos
* Marfan
* Nicoloau-Balus
* Brook-Spiegler
* Possible familial association (up to 20%)
Micro:
* Well circumscribed proliferation
* Epidermis unremarkable
* Epithelial cells forming ductules, nests, cysts and cords
* Cells are basaloid, cuboidal and double layered (in ductules) with an eosinophilic cuticle
* Ducts are often described as comma or tadpole shaped or in a paisley pattern
* May have cell clearing glycogen (clear cell syringoma), more common in diabetics
* Some small cysts may have squamous lining
* Usually in superficial reticular dermis, rarely deep dermal extension
* No cytologic atypia
* Very rare mitoses
Cutaneous mixed tumor / chondroid syringoma
- Benign adnexal tumor of the skin composed of mesenchymal and sweat gland components
- Morphologically identical to pleomorphic adenoma / benign mixed tumor of salivary gland
- Slow growing, painless nodule on head and neck
Macro:
* Nodular, circumscribed, nonulcerated, with marked variation in size
* Cut surfaces are tan-white, often with grossly apparent chondroid component
* Slow growing, painless, firm, deep dermal to subcutaneous nodule
Micro:
* Well circumscribed but unencapsulated
* Multilobulated mass (separated by fibrous septae) centered in deep dermis or subcutaneous fat
* Prominent chondroid or myxoid stroma enveloping benign bland appearing epithelial and myoepithelial cells that form secondary structures (glands, ducts, cysts, reticular lace-like networks, nests)
* Biphasic, with both epithelial and stromal components
* Epithelial: elongated branching tubular structures with 2 cell layers
Outer layer is cuboidal or columnar; inner layer is columnar with eosinophilic cytoplasm
Stroma: chondroid, mucoid or focally fibrous / hyaline
Molecular:
* Positive for gene rearrangement of PLAG1 in largest study to date but lacks the characteristic translocations of PLAG1 seen in pleomorphic adenoma of salivary gland
* HMGA2
Eccrine spiradenoma
- Benign neoplasm, excision is curative
- Predilection for head and neck
- Usually asymptomatic but can be painful
Micro:
* Circumscribed uninodular or multinodular basophilic tumor
* Mostly centered in the dermis (blue cannon balls)
* Some tumors are encapsulated
* Extension into the subcutis is common
* 2 cell populations in the neoplastic nodules: centrally located large pale cells and small dark basaloid cells at the periphery
* Neoplastic cells are arranged in trabecular, reticular or solid fashion
* Intratumoral lymphocytes as an integral component of the tumor
* Tubular / ductal structures (and PAS positive basement membrane material
* Stroma between the nests of epithelial cells is often edematous with prominent vascularity
Molecular:
* Association with the Brooke-Spiegler syndrome –> (CYLD gene)
Cylindroma
- Benign tumor with debated origin from eccrine sweat glands or hair follicles
- Also called turban tumor, particularly when a large, multicentric scalp tumor
- Solitary or multiple
- Primarily on head, neck and scalp
- Autosomal dominant, multiple tumors of children / teenagers that may also involve trunk and extremities
- Pink-red dome shaped nodule with smooth surface
Micro:
* Compact nests of basaloid cells that fit together like a jigsaw puzzle, surrounded by thick basement membrane
* Cylindrical shape appreciated in cross section
2 groups of cells:
* Undifferentiated peripheral palisading epithelial cells with small dark nuclei
* Centrally located increasingly differentiated ductal cells with large pale nuclei
Molecular:
* Mutation in CYLD on chromosome 16 associated with multiple familial cylindromas
* MYB gene mutations associated with sporadic cylindromas
* Chromosome 16 CYLD mutation common
Brooke-Spiegler Syndrome
Diagnostic Criteria:
* Early stage for onset skin neoplasms
* FHx of neplasms –> autosomal dominance pattern
* Cylindromas, spiradenomas or trichoepithelialiomas
* Increased association with tumours in parotid or salivary glands
* Genetic testing confirms mutation in CYLD gene
Syringocystadenoma papilliferum
- Benign adnexal tumor, most commonly occurring in the head and neck in early childhood
- Most are solitary papules but variable clinical presentation
Micro:
* Cystic invaginations of the epithelium projecting into the dermis, covered by a double cell layer
* Innermost layer is composed of columnar cells with decapitation secretion
* Outermost layer is composed of cuboidal cells with papillary projections
* Papillary fronds extend upward from the base and plasma cells are common in the stroma of each frond
Molecular:
Some cases have mutations in:
* Patched gene (PTCH)
* p16 tumor suppressor gene
