Diff Dx Cover

Papular mucinosis vs Interstitial granuloma annulare

Differential Diagnosis

Papular mucinosis Interstitial granuloma annulare
1. No loci of histiocytes in strikingly palisaded array 1. Loci of histiocytes sometimes in palisaded, as well as in interstitial, array
2. Mucin deposited either focally or diffusely 2. Mucin deposited focally, never diffusely
3. No degeneration of collagen and no nuclear “dust” of inflammatory cells 3. Degeneration of collagen and nuclear “dust” of inflammatory cells in the center of palisades of histiocytes
4. Oval and spindle-shaped fibrocytes constitute the dermal infiltrate 4. Plump oval histiocytes make up the dermal infiltrate
5. No elastophagocytosis 5. Elastic fibers sometimes present in the cytoplasm of histiocytes
6. Papillary dermis sometimes involved 6. Papillary dermis spared
7. Fibrosis in longstanding lesions 7. No fibrosis
8. Lymphocytes in epithelial structures of adnexa and in the epidermis at times 8. No lymphocytes in epithelial structures of adnexa or in the epidermis
9. Epidermis slightly acanthotic in some lesions 9. Epidermis unaffected
10. No involvement of the subcutaneous fat 10. Subcutaneous fat may be involved, sometimes extensively