Foreign Body Granuloma of the Skin
foreign body granuloma is a reaction to exogenous (foreign) or
endogenous materials that are too large to be ingested by macrophages.
These localized lesions may occur at any age and clinically present as papules, plaques or nodules.
Examples of granulomas due to exogenous material:
Starch- (Maltese cross birefringence in polarized light).
Talc - Birefringent
Suture material - (nylon, silk, dacron)- birefringent refractile multicoloured.
Wood splinter or bone fragment- Special stains for microorganisms should be performed to rule out infection due to contamination.
Plant material can be identified by PAS stain.
Arthropod bite can cause granulomatous reaction.
Silica (glass or sand), zirconium and beryllium elicit sarcoidal granulomatous reaction.
Tattoo material- Extracellular pigment is identified and may induce local sarcoidal granulomas.
Tetanus toxoid (aluminium-adsorbed vaccines) may induce foreign body reaction.
Granular debris at the centre surrounded by histiocytes and lymphoid infiltrate with follicle and eosinophils at the periphery.
May resemble Kimura's disease.
Silicone granulomas: A silicone granuloma is a tissue reaction elicited by silicone. Silicone granuloma in the breast arises from leakage of prosthesis.
Foreign body giant cells are present near lacunar spaces filled with amorphous refractile material.
Examples of granulomas due to endogenous material:
Keratin and hair : Granulomatous inflammation is present adjacent to ruptured epidermal and pilar cyst, pilomatrixomas and dermoid cyst.
Damaged hair follicle can elicit granulomatous reaction.
Fragments of keratin may be identified in the dermis.
Hair shafts are round or oval shaped on section, birefringent and Ziehl- Neelson stain positive.
Note: Foreign body reaction to keratin is an indication for a careful search for residual squamous cell carcinoma or recurrent tumour in a patient with history of carcinoma.
Initially there is suppuration around the foreign material.
This is followed by granulomatous inflammation which may be tuberculoid, sarcoidal, suppurative or necrobiotic type.
In the later stage there is fibrosis.
Around the foreign material there are histiocytes, some of these have differentiated into large cells with indistinct cell boundaries called epithelioid cells.
There are multinucleated giant cell of foreign body-type often containing ingested foreign material.
In foreign body giant cells the nuclei are scattered irregularly throughout the cytoplasm.
A few Langhans type of giant cells may be present, in which the nuclei are distributed along the periphery in a semicircle.
In most cases foreign material can be recognized in Hematoxylin and eosin stain sections.
In difficult cases (granulomatous inflammation of skin or panniculitis in which the nature cannot be diagnosed) polarized light should be used to identify birefringent foreign material.
Special stains for microorganisms are useful in establishing the diagnosis.
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