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In vertical growth, the large lesions, as encountered in this material, show areas in which vertical growth components are solid in patterns, somewhat similar to those of typical vertical growth with level III invasion in SSM. By Clark’s criteria, many of these lesions tend to show deep extensions to about the level of the sweat glands. Close inspection of the character of the interface between tumor and dermis usually shows areas in which thin fascicles extend into the reticular dermis among collagen bundles (level IV pattern; migrant or diffuse vertical growth) (c7t3P4 & 5, and c10t3P5-7).
In a third variation, the vertical growth components are relatively solid (c7t3P4 & 5, 7 & 8). For some of these lesions, the cells tend to be mostly rounded (“epithelioid”) (c7t3P7 & 8). Most of the lesions, tend to be uniformly, or focally, of a spindle cell character (c7t3P5, c8t3P5 & 6, c9t3P1 & 2, c10t3P5-7, c11t3P7, c12t3P1 & 2). Many of these lesions are uniformly, or focally, pigmented (c12t3P4-7); perhaps, the expression of this characterisitc may be influenced by the observation that the patient population is 70% black. Focally, some of the lesions are pleomorphic (c8t3P1, 5, & 6, c9t3P3, c10t3P8, c12t3P4, c13t3P4-7, c14t3P6-8); pleomorphism may be expressed in both radial and vertical growth components.
As examples of other variations, some lesions are composed of “epithelioid” cells that form thin fascicles; the fascicles are supported by a rich plexus of vessels (c13t3P3). Such lesions, if not pigmented, might be mistaken for metastatic carcinoma.
Some of the pleomorphic lesions show a poor definition of fascicular, or nesting patterns (c8t3P6, c12t3P2, c14t3P6-8 ). Fibrous strands may partition some of the nests. Such lesions might be mistaken for an atypical fibroxanthoma. In some lesions, the vertical growth patterns have a sarcomatoid quality with storiform qualities; such lesions must be distinguished from the mesenchymal forms of atypical fibroxanthoma (c14t3P7).
One lesion shows a sarcomatoid pattern that might be mistaken for that of a malignant soft tissue tumor (c14t3P8).
One lesion showed areas with prominent papillary patterns (c13t3P6 & 7).
Mixed patterns of differentiation are represented in many of the lesions (c10t3P3, c14t3P1-3).
Some of the lesions show multi-micro-nodular patterns of vertical growth in the reticular dermis (c9t3P3, c10t3P4); some of these patterns also are nevoid.
Some of the lesions show patterns that have desmoplastic qualities (c8t3P6, c11t3P7, c12t3P1 & 2, c14t3P6-8), but none of the lesions in this study showed patterns that would qualify the respective lesion as a desmoplastic melanoma.
The advanced nature of most of the lesions in this collection is documented in the clinical photographs. One of the lesions in this collection of photographs was small and flat (c15t3CP1). The other lesions are variable in size; many are large and ulcerated (c15t3CP2-9).
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