- Pink ball of spindle cells, 305
- Pink material, 308
- Pink dermis, 315
- Epidermal necrosis, 317
Myofibroma
- Pink ball of spindle cells (myofibroblasts)
- Some nuclei resemble those of smooth muscle cells with some cigar shapes
- Some nuclei resemble those of fibroblasts, with closely associated pink collagen
- Increased vessels, often particularly at the periphery of the pink ball
Key differences
(a)
(b)
(c)
(d)
- a, b Angioleiomyoma: smooth muscle cells with abundant cytoplasm, perinuclear vacuole, interspersed vessels (see page 178)
- c, d Myofibroma: cells resemble both fibroblasts and smooth muscle cells, peripheral vessels
(e)
(f)
(g)
(h)
- e, f Scar, hypertrophic: can sometimes form a “pink ball”; fibroblasts with closely associated collagen that may be keloidal
- g, h Schwannoma (neurilemmoma): encapsulated pink ball; cells are skinny and tapered; Verocay bodies and myxoid areas may be evident (see page 174)
Amyloid
- Amorphous pink material in upper dermis
- Plasma cells
Cryoglobulinemia (type I)
- Glassy, smooth pink material within vessels
- Minimal inflammation
Erythema elevatum diutinum (extracellular cholesterolosis)
- Pink material in the dermis with clefting (later lesions)
- Late stage has neutrophils interspersed with prominent fibrosis and “cholesterol clefts”
- Palisading of neutrophils and nuclear dust around altered collagen (earlier lesions)
- Swollen vessel walls and fibrin deposits (earlier lesions)
Pilomatricoma
- Pink material with shadows of nuclei within, may have a “butterscotch” color (“pilomatrical keratin”)
- Basaloid cells (not always present)
- Calcification or ossification may be present
- Giant cells often seen
Proliferating pilar tumor
- Pink material that is dense keratin
- Stratified squamous epithelium with no granular layer (tricholemmal differentiation)
Sclerotic fibroma
- Pink material arranged in a fenestrated or clefted fashion
- Hyalinized, relatively acellular collagen
Key differences
(a)
(b)
(c)
(d)
(e)
- Amyloid: amorphous pink material, plasma cells
- Erythema elevatum diutinum (late stage): fibrosis with clefting and interspersed neutrophils
- Pilomatricoma: shadow cells, basaloid cells
- Proliferating pilar tumor: dense pink keratin, no granular layer between keratin and epithelium
- Sclerotic fibroma: clefts between strands of sclerotic collagen
Radiation dermatitis
- Pink dermis
- Atypical, bizarre fibroblasts within dermis
- Dilated vessels with plump endothelial cells
- Adnexal structures often absent
Key differences
(a)
(b)
- Lichen sclerosus et atrophicus: pink band of dermis with inflammation below it (see also page 115)
- Radiation dermatitis: pink dermis with dilated vessels; atypical fibroblasts on higher power
Aspergillosis
- Epidermal and dermal necrosis
- Vessels necrotic with extravasated erythrocytes and visible fungal hyphae that are septate and branching
Burn
- Epidermal necrosis with variable dermal change
- Reversal of epidermal staining (more basophilic superficially than deep)
- Acute lesions are non-inflammatory
Erythema multiforme
- Epidermal necrosis below basket-weave stratum corneum
Herpes simplex infection
- Epidermal necrosis with acantholytic cells and multinucleated cells
- Follicular necrosis is a clue
Nutritional deficiency (zinc deficiency, acrodermatitis enteropathica, essential fatty acid deficiency)
- Epidermal necrosis or pallor underlying parakeratosis
- Basal layer relatively normal
- Inflammation not prominent
- Similar changes can be seen in necrolytic migratory erythema
Key differences
(a)
(b)
(c)
(d)
(e)
- Aspergillosis: epidermal and dermal necrosis with fungi in areas of destroyed vessels
- Burn: epidermal necrosis, sharp demarcation from normal skin
- Erythema multiforme: basket-weave stratum corneum, apoptotic keratinocytes
- Herpes simplex infection: acantholysis and multinucleated cells with rimmed chromatin (margination)
- Nutritional deficiency: parakeratosis above epidermal necrosis, basal layer often unaffected