{"id":5893,"date":"2020-09-15T11:10:52","date_gmt":"2020-09-15T01:10:52","guid":{"rendered":"https:\/\/mvec.mcri.edu.au\/?page_id=5893"},"modified":"2026-03-17T13:40:44","modified_gmt":"2026-03-17T02:40:44","slug":"%e0%a4%87%e0%a4%82%e0%a4%9c%e0%a5%87%e0%a4%95%e0%a5%8d%e0%a4%b6%e0%a4%a8-%e0%a4%b8%e0%a4%be%e0%a4%87%e0%a4%9f-%e0%a4%a8%e0%a5%8b%e0%a4%a1%e0%a5%8d%e0%a4%af%e0%a5%82%e0%a4%b2%e0%a5%8d%e0%a4%b8","status":"publish","type":"references","link":"https:\/\/mvec.mcri.edu.au\/hi\/references\/injection-site-nodules\/","title":{"rendered":"\u0907\u0902\u091c\u0947\u0915\u094d\u0936\u0928 \u0938\u093e\u0907\u091f \u0928\u094b\u0921\u094d\u092f\u0942\u0932"},"content":{"rendered":"
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The development of an injection site nodule (ISN) is a rare adverse event following immunisation (AEFI). Nodules can occur following administration of any injected vaccine.<\/span>\u202f\u202f<\/span><\/b>They usually present in the days or weeks following immunisation. ISNs are most often reported following vaccines given in infancy or childhood. An ISN usually persists for weeks or months. Very rarely, a nodule may persist for years. ISNs are most often asymptomatic, but may be intermittently tender, itchy, or show overlying skin changes (e.g. flaky skin). They generally resolve spontaneously, without treatment or investigation.<\/span><\/p>\n

Diagnosis<\/h2>\n

ISNs are defined as a firm, discrete or well-demarcated soft-tissue lump at the site of vaccination, in the absence of heat, erythema (redness) or signs of abscess (e.g. pus, pain). They are often described by parents and caregivers as a pea-size lump under the skin.<\/span><\/p>\n

Diagnosis is generally based on a healthcare provider\u2019s clinical assessment. Although not routinely recommended, some clinicians may request an ultrasound of the area to confirm or support the diagnosis, and to exclude alternative diagnoses. <\/span><\/p>\n

ISNs that last for months or years, with symptoms, are referred to as \u2018persisting subcutaneous nodules\u2019 (subcutaneous meaning under the skin). Itch is generally the concerning symptom that motivates people to seek medical attention. Ongoing scratching can alter the appearance of the skin leading to excoriation (irritated skin), hair growth and pigmentation changes. <\/span><\/p>\n

Intensified itching and an increase in size of the nodule can occur during the course of a viral illness, or following subsequent vaccinations administered at a different anatomical site.<\/span><\/p>\n

Association and incidence<\/h2>\n

It is unclear what causes an ISN<\/span>.<\/span> Factors identified as possibl<\/span>y<\/span> contributing to I<\/span>SNs include<\/span> administration technique, vaccine components (<\/span>including a<\/span>djuvants<\/span>,<\/span> such as aluminium<\/span>)<\/span>, patient predis<\/span>position and normal immune-mediated responses.<\/span><\/p>\n

There is limited data on ISN incidence rates. Some estimates are available based on small, local cohorts.<\/span><\/p>\n

The following references provide additional context on the possible causes and incidence of ISNs:<\/span><\/p>\n