New Frontiers in Pathology: An Update for Practicing Pathologists Case 8

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New Frontiers in Pathology An Update for
Practicing PathologistsCase 8

• Lori Lowe, M.D.
• University of Michigan
• Professor of Pathology Dermatology
• Director, Dermatopathology Service

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Case 8
Case History

• 68-year old male
• Long-standing, asymptomatic lesion
• Right upper lip
• Slowly growing
• Clinical impression cyst

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Diagnosis Microcystic Adnexal Carcinoma
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Microcystic Adnexal Carcinoma

• Background
• Rare, locally aggressive cutaneous adnexal
  neoplasm
• First described by Goldstein et al in 1982
• Synonyms
• Sclerosing sweat duct carcinoma
• Syringoid eccrine carcinoma
• Syringomatous carcinoma
• Nosologic confusion!

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Microcystic Adnexal Carcinoma

• Clinical Features
• Middle-aged to elderly patients
• Women gt men
• Poorly defined, slowly growing, firm,
  flesh-colored nodule or plaque
• Head and neck, especially upper lip and chin
• Clinically mistaken for scar, sclerosing basal
  cell carcinoma, cyst, or other adnexal tumor
• Generally asymptomatic for years

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Microcystic Adnexal Carcinoma

• Clinical Features contd
• Early detection uncommon
• Average tumor size at first diagnosis 2 cm
• Numbness, paresthesia, burning reported in
  long-standing lesions (perineural involvement)
• Propensity for subclinical extension
• Rate of local recurrence approaches 50
• Regional or distant metastasis rare
• 8 cases of metastasis, 1 reported death

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Microcystic Adnexal Carcinoma
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Microcystic Adnexal Carcinoma
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Microcystic Adnexal Carcinoma

• Histologic Features
• Sclerosing epithelial neoplasm with pilar and
  eccrine differentiation
• Infiltrative dermal neoplasm with frequent
  involvement of subcutis skeletal muscle ( 94
  cases)
• Small, cytologically bland, epithelial islands,
  cords and thin strands
• Keratotic cysts
• Glandular ductule lumina
• Neurotropism ( 82 cases)
• Associated desmoplastic stroma

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Microcystic Adnexal Carcinoma

• Microcystic Adnexal Carcinoma
• Infiltrative basaloid strands
• Desmoplastic stroma
• Keratotic cysts
• Ductule lumina
• Perineural invasion

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Microcystic Adnexal Carcinoma
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Microcystic Adnexal Carcinoma
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Microcystic Adnexal Carcinoma
Ductule Lumina
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Microcystic Adnexal Carcinoma
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Microcystic Adnexal Carcinoma
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Microcystic Adnexal Carcinoma

• Histogenesis
• Historically, tumor of putative pilar eccrine
  differentiation
• Cell of origin unknown
• Pluripotential adnexal keratinocyte capable of
  divergent differentiation vs. follicular-sebaceous
  -apocrine lineage
• Possible role of UV/radiation exposure
• Increased incidence on left side of face
• 8-12 cases have history of previous XRT

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Microcystic Adnexal Carcinoma

• Differential Diagnosis

• Dont be fooled.MAC can be a great mimicker!

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Microcystic Adnexal Carcinoma

• Differential Diagnosis
• Sclerosing (aggressive growth) basal cell
  carcinoma
• Adnexal neoplasms
• Syringoma
• Trichoadenoma
• Desmoplastic trichopithelioma

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Microcystic Adnexal Carcinoma vs.Sclerosing
Basal Cell Carcinoma
MAC
BCC
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Basal Cell Carcinoma, Aggressive Growth Pattern

• Peripheral palisading
• Retraction artifact
• Fibroblastic stroma

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Microcystic Adnexal Carcinoma vs.Sclerosing
Basal Cell Carcinoma
CK 15 positive (12/13)
CK 15 negative (10/10)
Ber-EP4 negative (13/13)
Ber-EP4 positive
Ber-EP4 positive 38 (5/13)
MAC
BCC
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Syringoma

• Benign adnexal neoplasm
• Derived from eccrine gland ductal epithelium
• Flesh-colored to yellowish, firm 1-3 mm papule(s)
• Periorbital distribution

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Syringoma

• Epithelial strands
• Tadpoles in dermis
• Ductule lumina
• Desmoplastic stroma

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Syringoma
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Microcystic Adnexal Carcinomavs.Syringoma
MAC
Syringoma
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Syringoma
MAC
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Trichoadenoma

• Benign adnexal neoplasm
• Follicular differentiation
• Small flesh-colored papule or nodule on face

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Trichoadenoma

• Epithelial islands
• Numerous keratinous cysts
• Resemble x-sections of follicular
  infundibulum

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Trichoadenoma
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Microcystic Adnexal Carcinoma
Case 8
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Microcystic Adnexal Carcinomavs.Trichoadenoma
MAC
Trichoadenoma
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Desmoplastic Trichoepithelioma

• Benign adnexal neoplasm
• Follicular differentiation
• Small flesh-colored plaque
• on face
• Mimics BCC clinically and histologically

Desmoplastic variant
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Desmoplastic Trichoepithelioma

• Horn cysts
• Thin basaloid strands
• Desmoplastic stroma

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Desmoplastic Trichoepithelioma (DTE)
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Desmoplastic Trichoepithelioma (DTE)
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Microcystic Adnexal Carcinomavs.Desmoplastic
Trichoepithelioma
CK 20 negative (8/8,13/13)
CK 20 positive (14/14)
CK 20 negative (7/8)
DTE
MAC
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Microcystic Adnexal Carcinoma

• Important Points
• Be aware of the many histologic mimickers
• Superficial biopsies particularly prone to
  misdiagnosis (reported in up to 30 of cases)
• Limited role for immunohistochemistry
• Dont hesitate to equivocate on the diagnosis if
  biopsy is inadequate!

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