Benign and Malignant Tumors

BENIGN EPIDERMAL AND DERMAL TUMORS
Seborrheic Keratosis (SK) (Figure 5.1A–C)
  • Common benign growth often seen after third decade of life
  • Typically light brown to yellow to dark brown papule or plaque with waxy or verrucous appearance and “stuck on” appearance
  • Histology: hyperkeratosis, papillomatosis, acanthosis of epidermis, horn pseudocysts, and often increased melanin in basal layer or throughout entire epidermis
  • At least five histological variants:
    • Acanthotic SK: most frequently seen histologic type; smooth domeshaped papule with slight hyperkeratosis/papillomatosis but significant acanthosis and many invaginated horn pseudocysts, increased amount of melanin within keratinocytes
    • Hyperkeratotic SK: exophytic lesion with significant hyperkeratosis and papillomatosis, only mild acanthosis, fewer horn pseudocysts
    • Reticulated (adenoid) SK: interlacing thin strands of basaloid cells and horn pseudocysts
    • Clonal SK: intraepidermal well-defined nests of basaloid cells with uniform appearance
    • Irritated SK: squamous eddies (whorls of eosinophilic keratinocytes) within epidermis, ± scattered necrotic keratinocytes, lymphoid infiltrate (lichenoid, perivascular or diffuse)
    • Pigmented SK (melanoacanthoma): acanthotic, heavily pigmented SK
  • Treatment: reassurance, cryotherapy, curettage, shave removal, laser treatment
   
 
Sign of Leser-Trelat: sudden eruption of SKs typically on trunk and associated with underlying adenocarcinoma (i.e., stomach, colon, etc.)
 
   
Figure 5.1 A: Seborrheic keratosis B: Seborrheic keratosis C: Multiple SKs
Figure 5.1
A: Seborrheic keratosis
B: Seborrheic keratosis
C: Multiple SKs