Skin nontumor

Dermal granulomatous and necrobiotic reaction patterns

Foreign body reaction

Editorial Board Member: Viktoryia Kozlouskaya, M.D., Ph.D.
Matthew Franklin, M.D.
Stephen Somach, M.D.

Last author update: 26 July 2022
Last staff update: 26 July 2022

Copyright: 2002-2024,, Inc.

PubMed Search: Foreign body reaction

Matthew Franklin, M.D.
Stephen Somach, M.D.
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Cite this page: Franklin M, Somach S. Foreign body reaction. website. Accessed May 19th, 2024.
Definition / general
  • Inflammatory response, most often granulomatous, to an exogenous or endogenous substance that is regarded as foreign material by the cutaneous immune system
Essential features
  • Foreign body reaction refers to the inflammatory response of the cutaneous immune system to either exogenous material or an endogenous substance that is altered in some way so that it is regarded as nonself / foreign
  • Foreign material may be introduced intentionally (such as tattoos of cosmetic fillers) or accidentally (such as metals or minerals at sites of trauma) (Dermatol Clin 2015;33:497)
  • Keratin is one of the most common substances to elicit a foreign body reaction, as it is typically confined to immune privileged sites
  • Though other reaction patterns to foreign material can be seen, granulomatous is the most common (Int J Dermatol 1984;23:531)
  • Foreign body granuloma refers to foreign body reaction with granulomatous inflammation, which is the most common pattern
ICD coding
  • ICD-10: L92.3 - foreign body granuloma of the skin and subcutaneous tissue
  • Any site can be affected but sites of cutaneous injury most commonly affected
  • Exogenous material or endogenous material typically hidden from the immune system (e.g. follicular keratin) becomes exposed to innate immune system through trauma (e.g. accidental injury, injection, surgery, tattooing), topical application or systemic exposure
  • Initial response is a neutrophilic infiltrate, which typically fails to deal with the foreign material (Dermatol Clin 2015;33:497)
  • Local tissue reactions may be lichenoid, eczematous or pseudolymphomatous; however, granulomatous is the most common reaction pattern seen with foreign bodies (Br J Dermatol 1995;133:665, Biomed Res Int 2014;2014:354608, Int J Dermatol 1984;23:531)
  • Granuloma formation:
  • Exposure of immune system to exogenous material or an endogenous substance that is typically protected from the immune system
Clinical features
  • Varies with the nature of the exposure to the foreign body and specifics of the host response
  • Typically, an acute inflammatory response with erythema and pain is the earliest finding
  • Resolves over weeks, months or even years
  • Subsequently, a chronic inflammatory response may develop if the acute response did not entirely clear the foreign material
  • Red to brown papules, plaques and nodules, along with variable ulceration, may be seen
  • Fibrosis may result in tissue induration
  • Configuration of lesion(s) may a be clue to causative agent
  • Pyogenic granuloma-like lesions (Cases J 2009;2:7354)
  • Pseudofolliculitis barbae (Dermatol Clin 1988;6:407)
  • Foreign material may contain microorganisms (Arch Dermatol 1984;120:1209, Cutis 1995;56:41)
  • Associated lymphadenopathy may secondary to granulomatous inflammation and foreign material in lymph node (Oral Surg Oral Med Oral Pathol 1985;59:449, J Clin Pathol 2000;53:549)
  • Careful history and examination correlated with tissue sampling and exclusion of other diagnoses (e.g. granulomatous disease, infection)
  • Ultrasound can quantify the severity of tattoo reactions (Skin Res Technol 2014;20:257)
  • Identification of foreign substance can be ascertained using ultrastructural analytic techniques such as energy dispersive Xray spectroscopy / analysis (Clin Dermatol 1991;9:157)
Radiology description
  • Ultrasound
    • Prominent echolucent band, the thickness of which correlates with thickness of cellular infiltration on histology (Skin Res Technol 2014;20:257)
Case reports
Clinical images

Images hosted on other servers:

Tongue nodule

Lower lip nodule

Microscopic (histologic) description
  • Varies depending on the specific response but many materials (e.g. silica, tattoo pigments, zinc, keratin, zirconium, silicone etc.) produce sarcoidal granulomas (Int J Dermatol 1984;23:531):
    • Discrete aggregates of epithelioid histiocytes and multinucleate giant cells (Langhans or foreign body type)
    • Sparse rim of surrounding lymphocytes and plasma cells
  • Specific patterns (Clin Dermatol 1991;9:157, Int J Dermatol 1984;23:531):
    • Tattoo: may see pigment within macrophages and in interstitium
    • Paraffin: cystic spaces of varying size (swiss cheese), which stain with oil red O on fresh tissue
    • Silicone: cystic spaces of varying size (swiss cheese), which do not stain with oil red O on fresh tissue
    • Silica: crystalline particles that are birefringent on polarized light
    • Talc: birefringent particles with polarized light
    • Starch: birefringent particles with Maltese cross shape on polarized light; stains with PAS
    • Zinc: birefringent particles with polarized light
    • Bovine collagen: stains pale gray-violet (rather than blue-green) with Masson trichrome
    • Hyaluronic acid: stains blue with high pH Alcian blue
    • Wood splinter: regularly sized cells on cross section
    • Keratin: potato chip bodies that are variably birefringent
Microscopic (histologic) images

Contributed by Matthew Franklin, M.D.
Granulomatous inflammation

Granulomatous inflammation

Foreign body giant cells

Foreign body giant cells

Splinter with inflammation Splinter with inflammation

Splinter with inflammation

Virtual slides

Images hosted on other servers:

Talc granuloma

Foreign material in orbit

Positive stains
  • CD68 stains multinucleate giant cells

Histopathology of breast foreign body reaction

Sample pathology report
  • Skin, left dorsal forearm, punch biopsy:
    • Tattoo with foreign body reaction (see comment)
    • Comment: Sections show a bisected punch specimen with an unremarkable epidermis with subjacent dermal scar. Underlying the dermal scar, there is a broad, well demarcated zone of granulomatous inflammation with numerous multinucleate giant cells and scattered lymphocytes. Black pigment is identified within histiocytes and in the surrounding interstitium. The findings are those of a granulomatous foreign body reaction and could be consistent with a prior traumatic tattoo. Clinical correlation is recommended.
Differential diagnosis
  • Sarcoidosis:
    • Exclude foreign material and infection (e.g. with microscopic examination with polarized light and stains for microorganisms)
  • Infection (e.g. abscess):
  • Pyogenic granuloma:
    • May arise in the setting of a foreign body reaction
    • Exclude an underlying foreign body reaction (e.g. with careful history and microscopic examination with polarized light)
Board review style question #1

The photomicrograph shown above depicts an excision specimen from a carpenter presenting with a painful nodule of the right palm. What is the diagnosis?

  1. Epidermoid cyst
  2. Foreign body granuloma
  3. Osteoma cutis
  4. Pilomatricoma
Board review style answer #1
B. Foreign body granuloma

Comment Here

Reference: Foreign body reaction
Board review style question #2
Which inflammatory pattern is most commonly seen in a foreign body reaction?

  1. Eczematous
  2. Granulomatous
  3. Lichenoid
  4. Psoriasiform
Board review style answer #2
B. Granulomatous

Comment Here

Reference: Foreign body reaction
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