Mucinoses

Deposition of glycosaminoglycans (GAGs) within the skin (dermis, usually)
  • Most often, deposit is composed of hyaluronic acid
  • Often associated with:
    • Thyroid
    • Infections
    • Gammopathy
    • Diabetes mellitus
    • Lupus erythematosus
 
Classification
  • Primary - mucin deposition is the major histologic feature
    • Degenerative-Inflammatory
      • Dermal
        • Scleredema
        • Scleromyxedema
        • Papular mucinosis
        • Mucinosis associated with altered thyroid function
          • Pretibial Myxedema
          • Generalized Myxedema
        • Reticular erythematous mucinosis
        • Papulonodular mucinosis
      • Follicular
        • Follicular mucinosis
    • Hamartomatous-neoplastic
      • Mucinous nevus
      • (Angio)myxoma
  • Secondary - mucin simply represents an associated histologic finding
 
Stains
  • Alcian blue
  • Colloidal iron
  • Toluidine blue
  • PAS negative
 

Scleredema

  • Type 1
    • Middle-aged women
    • Preceded by strep infection (or other non-specific upper respiratory infection)
    • Cervicofacial
    • Self-limited
  • Type 2
    • Similar to type 1 but more subtle and persistent
    • Monoclonal gammopathy
  • Type 3
    • Obese men with insulin-dependent DM
    • Posterior neck and back
    • Difficult to treat, not self limited
  • Clinical presentation
    • Symmetric diffuse induration of the skin
    • Skin may have peau d’orange appearance
    • Prominent follicular openings, due to deposition of mucin around hair follicles
    • Patients may complain of tightness or decreased range of motion in the affected areas

Scleromyxedema

  • Monoclonal gammopathy
    • IgG - lamda light chains
  • Systemic manifestations similar to amyloidosis
  • Waxy papules in linear array
    • Donut sign - deposition around the knucke forming a central depression
  • Diffuse infiltration of the skin with thickened folds
    • Deep glabellar furrows
    • Sinal de Shar-Pei
    • Leonine facies
  • Localized form is papular mucinosis

Papular Mucinoses “Localized Scleromyxedema”

  • Different variants → key is to associate associated infections and gammopathies
    • Discrete papular lichen myxedematosus
    • Acral persistant papular mucinosis
        • notion image
      • Skin colored to tan papules in the dorsal aspects of the hands
    • Cutaneous mucinosis of infancy
    • Nodular lichen myxedematosus
    • Localized lichen myxedematosus in HIV-infected patients, HCV, or in toxic syndromes

Pretibial Myxedema

  • Associated with hyperthyroidism and Grave’s disease
    • Increased metabolism in hyperthyroidism → increased mucin deposition
  • Skin lesions may appear following treatment of thyroid disease. Treating the thyroid disorder doesn’t always revert the pretibial myxedema
  • Clinical presentation
    • Purple-black plaques on the shins of a patient with Graves
    • Peau d’Orange - due to mucin deposition around the hair follicles → prominent follicular openings

Generalized Myxedema

  • Associated with profound hypothyroidism (usually hashimoto)
    • Congenital, juvenile or adult
  • Clinical presentation
    • Skin is dry, cool and pale with waxy appearance
    • Hair and nails can be brittle → can lead to diffuse non-scarring alopecia of the scalp and lateral eyebrows
    • Weight gain, cold-intolerance, constipated and sluggish

Reticular Erythematous Mucinosis (REM)

  • Reticulated and annular patches and plaques on back and chest
  • No surface changes
  • Can be photoaggravated
  • Overlaps with Lupus Erythematosus Tumidus, Lymphocytic Infiltrate of Jessner with minimal to no dermal mucin and papulonodular mucinosis
  • Treatment
    • Topical or intralesional steroids
    • Antimalarials

Cutaneous Lupus Mucinosis/Papulonodular Mucinosis

  • Clinical presentation
    • Asymptomatic papules and nodules
    • Lumpy appearence
    • Back, chest, upper extremities (photoexposed sites)
  • 75% of Lupus patients who develop these lesions have systemic involvement → think about SLE!

Follicular mucinoses

  • Usually in children
  • Mucin deposited within the epithelium of hair follicles rather than in the dermis
  • Pink to violet to brown plaques
  • Primarily in the head and neck region
  • Associated alopecia
  • Sometimes some scaling
  • Grouped follicular papules
  • Primary form in children and young adults → benign and self limiting
  • Older adults with more widespread and persistent lesions → possible co-existing mycosis fungoides or CTCL
  • Histology: mucin within follicular epithelium leading to alopecia
    • Look for atypical lymphocytes if you suspect MF