Differentials
Acne vulgaris
SIGNS / SYMPTOMS
Typically occurs on the face, chest, and back. Morphology of lesions can be indistinguishable from HS lesions. However, acne vulgaris rarely results in draining sinus tracts.[2]
INVESTIGATIONS
No distinguishing tests.
Crohn's disease
SIGNS / SYMPTOMS
Fistulas and sinus tracts are usually perianal in distribution. Patients may experience gastrointestinal symptoms, such as bloody diarrhoea, abdominal cramps, and lower abdominal pain.[2]
INVESTIGATIONS
Endoscopy and biopsy will show inflammation with disruption of crypt architecture; non-caseating granulomas may be present.
The presence of granulomas on skin biopsy is suggestive, but not diagnostic, of cutaneous Crohn's disease.
Inverse psoriasis
Epidermal inclusion cyst
SIGNS / SYMPTOMS
Typically presents as a solitary lesion, which usually has a visible punctum at the surface. Inflammation is common.[2]
INVESTIGATIONS
Excisional biopsy is diagnostic and therapeutic.
Furunculosis
SIGNS / SYMPTOMS
Presents as a solitary abscess, often with a collarette of fine scale. More often presents after abrasion of the skin or in immunocompromised patients.[2]
INVESTIGATIONS
Bacterial culture will demonstrate pathogenic bacteria: for example, Staphylococcus aureus, often MRSA.
Lymphogranuloma venereum
SIGNS / SYMPTOMS
Sexually transmitted disease caused by Chlamydia trachomatis. Typically presents as a suppurative inguinal adenitis with pronounced lymphadenopathy that shows a characteristic groove sign.[2]
INVESTIGATIONS
Complement fixation test will show a titre >1:64 or a 4-fold rise between acute and convalescent specimens. However, complement fixation with a high titre in the absence of symptoms does not confirm lymphogranuloma venereum, and a low titre does not exclude it.
Squamous cell carcinoma
SIGNS / SYMPTOMS
Usually ulcerated. May be a complication of HS.
INVESTIGATIONS
Skin biopsy will show evidence of malignancy with foci of keratinisation and formation of squamous whorls where the neoplastic cells tightly wrap around each other.
Use of this content is subject to our disclaimer