Mucins are jelly-like acid glycosaminoglycans (formerly known as mucopolysaccharides) of the ground substances and probably play a part in the extravascular exchange of metabolites. Mucin is normally produced in small quantities by fibroblasts. Acid glycosaminoglycans, such as hyaluronic acid and heparin, stain with toluidine blue, colloidal iron, or with alcian blue at pH 2.5, the coloration depending on the number and nature of the acid groups. PAS stains heparin, but not hyaluronic acid. In general, acid glycosaminoglycans stain much brighter in frozen fixed tissue, or in 1% cetylpyridinium chloride solution, rather than in formalin-fixed biopsies. Classification of the cutaneous mucinoses: 1- Primary 2- Secondary

1. MUCINOSES
BY
Dr. Saad Raheem Abed

2. Mucinoses
Mucins are jelly-like acid glycosaminoglycans (formerly
known as mucopolysaccharides) of the ground
substances and probably play a part in the extravascular
exchange of metabolites. Mucin is normally produced in
small quantities by fibroblasts. Acid glycosaminoglycans,
such as hyaluronic acid and heparin, stain with toluidine
blue, colloidal iron, or with alcian blue at pH 2.5, the
coloration depending on the number and nature of the
acid groups. PAS stains heparin, but not hyaluronic acid.
In general, acid glycosaminoglycans stain much brighter
in frozen fixed tissue, or in 1% cetylpyridinium chloride
solution, rather than in formalin-fixed biopsies.

3. Classification of the cutaneous
mucinoses
 Primary
 Diffuse (degenerative-inflammatory mucinoses)
 Generalized myxoedema
 Pretibial myxoedema
 Lichen myxoedematosus (papular mucinosis,
scleromyxoedema)
 Reticular erythematous mucinosis (plaque-like mucinosis)
 Scleroedema
 Self-healing juvenile cutaneous mucinosis
 Cutaneous mucinosis of infancy
 Papular and nodular mucinosis associated with lupus
erythematosus
 Papular mucinosis of the toxic oil syndrome

4. Primary
 Focal (neoplastic-hamartomatous mucinoses):
-Cutaneous focal mucinosis
-Mucous (myxoid) cyst
-Acral persistent papular mucinosis
-Mucinous naevus
 Follicular forms:
-Follicular mucinosis (alopecia mucinosa)
-Urticaria-like follicular mucinosis

5. Secondary
-Collagen vascular diseases (especially
dermatomyositis, lupus erythematosus)
-Malignant atrophic papulosis (Degos’ syndrome)
-Hereditary progressive mucinous histiocytosis
-Papular mucinosis in L-tryptophan-induced
eosinophilia–myalgia syndrome
-Mucinosis accompanying mesenchymal and
neural tumours

6. Lichen myxoedematosus syn. papular mucinosis; lichen
fibromucinodosis; scleromyxoedema
Lichen myxoedematosus is a cutaneous myxoedematous state
characterized by the formation of numerous lichenoid papules which
coalesce together to form generalized plaques, causing extensive
thickening and hardening of the skin. It is a rare disorder
characterized by proliferation of fibroblasts with fibrosis and
excessive deposition of acid glycosaminoglycans in the skin, and is
distinct from scleroderma. Montgomery and Underwood divided it
into four types:
 1 a generalized lichenoid papular eruption (scleromyxoedema);
 2 a discrete papular form;
 3 a localized to generalized lichenoid plaque form; and
 4 an urticarial plaque form.

7. A recent review of this area suggests that
there are really only two main divisions of lichen
myxoedematosus, a generalized papular and
sclerodermoid form (scleromyxoedema) and a
localized papular form.
Scleromyxoedema is usually associated with a
monoclonal gammopathy.
Serum from patients with lichen myxoedematosus,
even after elution of the IgG paraprotein, can
stimulate synthesis of DNA and cell proliferation in
cultured fibroblasts.
Localized forms of lichen myxoedematosus, without
ademonstrable paraprotein, are recognized, and
include a discrete papular form involving any site.

8. acral persistent papular mucinosis involving
only the extensor surface of the hands and
wrists.

9. PHYSICAL FINDINGS:
Scleromyxedema
 In scleromyxoedema (the Arndt–Gottron syndrome)
the pattern of lichen myxoedematosus is confluent,
papular and sclerotic. Flesh colored to yellow/red,
papular skin eruption, Indurated with a cobblestone
feel
 Distribution includes head, posterior auricular area,
neck, arms and trunk
 Midportion of back can be involved
 NOT involved in scleroderma
 Sclerodactyly can be present on the hand, simulate
the sclerodactyly of scleroderma , but the clinical
appearance of numerous small papules of more or
less uniform size, often in linear patterns on an
erythematous and palpably thickened background, is
very distinctive.

10. Fig. Lichen myxoedematosus. Close up
of micropapules behind earlobe.
Fig. Scleromyxoedema. View of
forehead showing sclerodermoid
appearance and linear papulation.

11. Fig.Scleromyxoedema. Sclerodermoid appearance
of finger.

12. Fig.Scleromyxoedema. Sclerodermoid appearance
of face

13. Fig.Scleromyxoedema. Sclerodermoid appearance of neck
and chest.

14. Histopathology
Mucinous deposits occur in the middle and deeper
layers of the dermis, where they displace
collagen fibres, but do not involve the dermal
papillae or accumulate around blood vessels.
Histochemically,the mucinous deposits are
heterogenous mixtures of acid
glycosaminoglycans, which stain positively with
alcian blue and toluidine blue. Large, stellate,
elongated fibroblasts are present within the
mucinous stroma .
Mucin deposition in the media and adventitia of
vessels and in many organs including the

15. Diagnosis.
Infiltrates appearing in and around old scars may
simulate ‘scar sarcoidosis’. Papules on the
dorsa of the hands and ears may cause
confusion with granuloma annulare. Systemic
scleroderma may show many features
simulating scleromyxoedema. However, in
scleroderma the skin is thickened and bound-
down, whereas in scleromyxoedema it is also
thickened but moveable over the subcutis.
Papules are absent in scleroedema and
scleroderma, but common in
scleromyxoedema.

16. Prognosis.
The prognosis of scleromyxoedema is poor
despite the introduction of treatment with
cyclophosphamide and melphalan.
Death may result from non-specific
complications such as bronchopneumonia,
coronary occlusion or from haematological
malignancies

17. LABORATORY DATA:
Scleromyxedema
 Monoclonal gammopathy with lambda chains
 Level of paraprotein does not decrease after
effective treatment
 Pathogenesis unclear
 Mucinous deposition throughout the dermis
 Thick collagen bundles
 Increased fibroblast-like cells
 Inflammatory infiltrate
 Autoimmune markers typically negative

18. TREATMENT: Scleromyxedema
 Variable immunosuppressants have been tried
 IVIG 2g/kg monthly for 2-3 months then
maintenance every 10-12 weeks
 Melphalan
 Cyclophosphamide
 Cyclosporine
 Thalidomide
 Stem cell transplant has been used