After reticular lines, the pattern of clods is the second most common.
- White and/or yellow clods: Seborrheic keratosis, dilated infundibula and inclusion cysts ("milia") filled with keratin, sebaceous gland hyperplasia. Radial vessels which do not cross the center of the lesion are a strong clue to sebaceous gland hyperplasia.
- Orange clods: Seborrheic keratosis, or basal cell carcinoma (orange clods due to ulceration (serum crust)). Whereas multiple orange clods are seen in seborrheic keratosis, in basal cell carcinoma one usually finds one or two orange clods with traces of red due to red blood cells in the serum crust. A further clue is the pattern of vessels: in basal cell carcinoma serpentine vessels, often branched; in seborrheic keratosis, looped or coiled vessels (or rarely serpentine).
- Red or purple clods: hemangioma or vascular malformations.
- Black clods: Thrombosed vessels
- Red clods: Hemorrhage
- Large, polygonal skin-colored clods:exophytic congenital nevi with papillomatous surface (Unna nevus or Miescher nevus), or verrucous seborrheic keratosis.
- Brown clods: various types of melanocytic nevi.
- Large, polygonal light-brown clods: Unna nevus or Miescher nevus
- Small to medium-sized, round and oval brown clods: small congenital nevi, of "superficial" and "superficial and deep" types. Central hyperpigmentation is common in pigmented Spitz nevi, and peripheral clods are usually smaller than those in the center.
- Blue clods: pigmented basal cell carcinoma.Differential diagnoses: While melanoma and combined congenital nevus.
More than one color Necessary to distinguish between the colors of melanin and the colors of other pigments Clods whose pigmentation is due to melanin are brown, blue or gray.
- Black clods: blood pigment hemoglobin.
- White, yellow or orange clods: keratin with (orange) or without (white or yellow) inclusions of melanin. Orange clods may also result from ulceration (serum crust).
- White or yellow clods are mainly found in seborrheic keratoses and less often in Unna nevi. Orange clods also indicate a seborrheic keratosis or less often an Unna nevus.
- Combination of red, purple or black clods: hemangioma, vascular malformation or hemorrhage.
- Clods + colors of melanin (brown, blue or gray): symmetry of color distribution is assessed next.
- Clods with symmetrical color distribution: melanocytic nevi, i.e. superficial and deep congenital nevi, combined congenital nevi, Unna nevi and pigmented Spitz nevi
- Clods with asymmetrical color distribution: pigmented basal cell carcinoma and melanoma.