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General tips

Erythema annulare centrifugium (EAC) is a chronic condition that usually presents as a reaction to an antigen.
Many underlying conditions have been reported to be associated with EAC but in most of cases, the underlying antigen can`t be identified.
It can occur at any age.

History taking:

Fungal infection
- Dermatophytoses, Candida, Penicillium in blue cheese.
Bacterial infection
- Mycobacteria, streptococci, Escherichia coli, syphilis, Pseudomonas septicaemia.
Viral infection
- Epstein–Barr virus, HIV, herpes simplex, herpes zoster , molluscum contagiosum, viral hepatitis.
Parasitic infection
- Ascaris lumbricoides, Phthirus pubis.

Non‐steroidal anti‐inﬂammatory drugs.
Antimalarials.
Diuretics : hydrochlorothiazide, spironolactone.
Antibiotics : Ampicillin, co‐trimoxazole, penicillins.
Others : Acetazolomide, amitriptyline,cimetidine,finasteride, rituximab, pegylated interferon-α-2a plus ribavirin, ustekinumab.

It typically precedes the clinical diagnosis of malignancy, and may recur with subsequent relapses.

Skin tumor : Squamous cell carcinoma
Hematological : Acute myelogenous leukaemia, chronic lymphocytic leukaemia , hypereosinophilic syndrome , lymphomas, myeloma.
Internal : Breast, bronchial, naso‐pharyngeal, ovarian, prostatic and gastric carcinomas.

Autoimmune hepatitis, lupus erythematosus, polyglandular autoimmune disease type 1 , relapsing polychondritis , Sjögren syndrome.

Appendicitis , cholestatic liver disease, inﬂammatory bowel disease, sarcoidosis, hyperthyoidism.

Two type of erythema annulare centrifugium have been descibed

Superficial type:
- It usually starts as firm pink papules that expand centrifugally followed by central clearing.
- It enlarges gradually and it may reach few centrimetres in diameter.
- It may form annular, polycyclic palques or patches or incomplete arcs.
- The inner margin shows trailing scale (desquamation).
- The lesions may be pruritic.
- Vesicles may be sometimes seen on the border.
Deep type:
- The edge is slightly elevated ane the lesions are more indurated.
- No trailin scales.
- No pruritus.

Affected body parts

Exclude dermatophytes infection because it is one of the most common associations( KOH- culture)
Biopsy with direct immunoﬂuorescence to exclude other similar annular diseases.
Full blood count : to evaluate a suspected underlying infection (neutrophilia with bacterial infection; eosinophilia with parasitic infection or hypereosinophilic syndrome).
Liver and thyroid function tests : to exclude hepatitis and hyperthyoidism.
Chest X‐ray : to exclude tuberculosis, malignancy (primary or metastatic), sarcoidosis, or lymphoma.
An antinuclear antibody profile for lupus.
Serum angiotensin‐converting enzyme (ACE): for sarcoidosis.
HIV serology
If malignancy suspected, PET-CT should be considered.

Erythema annulare centrifugium should be differentiatied from the different annular conditions such as:

Tinea corporis and tinea imbricata
- Clinically,pruritic and scaly. The scales are usually on the leading edge not the trailing one.
- KOH and culture can exclude fungal infection.
Granuloma annulare
- No scales.
- Biopsy can be done to differentiate, granuloma annulare shows an interstitial and/or palisaded, histiocytic infiltrate with or without collagen necrobiosis.
Erythema marginatum
- The patient usually will be a child with acute rheumatic fever.
- Annular erythematous plaques appear rapidly then fade over the course of hours to several days.
Erythema migrans
- Expanding erythematous patch usually surrounding a central bite site with central clearing, occurs ~1-2 weeks after tick bite.
- It disappears typically within 4 weeks without treatment.
- Patients may have associated fatigue and lymphadenopathy.
- Histopathology and serology can be used to differntiate.

Erythema gyratum repens
- Gyrate polycyclic plaques with trailing scale.
- Itchy.
- A strong association with Various malignancies, bronchogenic carcinoma is the most common.
- Pathologically different from EAC.
Erythema papulatum centrifugum
- Itchy and sweat related condition.
- It presents as annular plaues with the border formed of multiple small papules.
- Pathologically,biopsy shows inflammation around dermal and intraepidermal eccrine ducts.
Erythema multiforme
- acute presentation of target lesions affecting mostly the acral parts.
- Mucous memebranes may be affected.
- Lesions may show vesicles or bullae.
Subacute cutaneous lupus erythematosus
- The lesions usually affects the sun exposed skin.
- Biopsy and serology can be done to differentiate.
Annular secondary syphilis
- If suspected, rapid plasma reagin (RPR) can be done.
Annular sarcoidosis
- Naked granuloma can be seen on biopsy.
- Other organ affection like pulmonary sarcoidosis may be present.
Necrolytic migratory erythema
- It is assocaited with Glucagonoma syndrome, pancreatic tumor can be detected by CT scan.
- Patients may be present with weight loss, diarrhea, anemia and diabetes mellitus.
- The distribution of the lesions tends to be perioral, perianal, and in the inguinal folds
Annular urticaria
- Urticarial lesions usually fades in less than 24 hours.
Urticarial phase of bullous pemphigoid
- Older patients are affected.
- Biopsy can be used to confirm the diagnosis.

Erythematous annular lesions expanding centrifugally followed by clearing of the center.
Trailing scales on the inner edge of the lesion border.
Pathological features of superficial type is not specific, but deep type may show tight aggregate around vessels, the so-called “coat sleeve” appearance.
Histopathogical features can help to exclude other annular diseases.

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