Under-skin nodule: what are the treatment options?

Nodules can initially be managed with topical treatments, including:

• Corticosteroids.

  In the event of inflammatory nodules, some dermatologists prescribe corticosteroid creams to reduce the inflammation and swelling of the nodules. These anti-inflammatories work by binding to specific cellular receptors, thereby inhibiting the production of pro-inflammatory cytokines and prostaglandins, which are mediators of inflammation. Corticosteroids can also slow the migration of immune cells and stabilise the membranes of lysosomes, which limits the release of enzymes that degrade tissues. Like all medications, corticosteroids can cause side effects, such as skin atrophy or pigmentation disorders, hence the importance of closely following the recommendations of one's dermatologist.

• Topical Retinoids.

  Derivatives of vitamin A, retinoids are a molecular class frequently used to combat acne, including nodular acne. By binding to specific nuclear receptors of retinoids RAR and RXR, they modulate the expression of genes related to cell growth. Thus, retinoids help to normalise the desquamation of epidermal cells and assist in unclogging hair follicles, thereby reducing the formation of new nodules. They also have anti-inflammatory properties. Although the desire is often to make nodules disappear quickly, applying an excessive amount of retinoid-based cream to the skin brings no additional benefit. On the contrary, it increases the risk of local irritation.

• Topical Antibiotics.

  Used for their antibacterial and anti-inflammatory properties, antibiotics such as clindamycin or erythromycin are effective in reducing bacterial populations at the nodule level. For instance, clindamycin works by inhibiting the synthesis of certain proteins essential to bacterial metabolism, thereby limiting the proliferation of these microorganisms responsible for inflammation. This type of treatment has the advantage of carrying a low risk of side effects.

It is also possible to treat inflammatory nodules using oral medications.

• Oral Antibiotics.

  Oral antibiotics, such as doxycycline or minocycline, are commonly prescribed to treat nodules of infectious origin or those accompanied by significant inflammation. These drugs primarily work by inhibiting the proliferation of pathogens that colonise the sebaceous glands and promote inflammation, such as Cutibacterium acnes. Antibiotics inhibit the synthesis of bacterial proteins by binding to ribosomal subunits, thus preventing the multiplication of microorganisms. It is quite common for oral antibiotics to be prescribed in conjunction with topical retinoids.

• Isotretinoin.

  A derivative of Vitamin A, isotretinoin is a gold-standard oral treatment for severe acne and persistent inflammatory nodules. Its mechanism of action is multifaceted. This molecule directly targets the sebaceous glands, reducing their size and activity, and normalises the keratinisation process, thereby reducing the risk of hair follicle obstruction. Furthermore, isotretinoin decreases the expression of pro-inflammatory cytokines, helping to soothe inflammation at the nodule level. Despite its proven efficacy, isotretinoin requires special attention due to its potential side effects, including skin and eye dryness, musculoskeletal disorders, and teratogenic risks in women. Regular medical check-ups and monthly blood tests are therefore required throughout the treatment.

Finally, certain aesthetic medicine and surgical techniques allow for the rapid removal of nodules.

• Surgical excision.

  Surgical excision is a traditional method for removing large inflammatory nodules or those suspected to be malignant. This technique involves the complete removal of the lesion using a scalpel or a surgical knife, followed by suturing and the application of healing care to promote rapid recovery. When the nodule is suspected to be cancerous, a histopathological analysis is carried out. Surgical excision is usually performed on an outpatient basis and requires at least minimal local anaesthesia.

• Cryotherapy.

  Cryotherapy is a minimally invasive technique used to eliminate relatively shallow nodules. It involves the application of liquid nitrogen to the nodules, which lowers the temperature of the skin tissues. Their rapid cooling leads to the formation of ice crystals inside and around the cells, causing the rupture of cell membranes and their destruction. Cryotherapy also stimulates cell regeneration, leading to a gradual repair of tissues and the disappearance of the nodule. It should be noted that, in some cases, several cryotherapy sessions may be necessary.

• The CO2 laser.

  Renowned for its high precision, the CO2 laser is particularly recommended for localised or recurring nodules. It utilises an infrared light beam, emitting at a wavelength of 10.6 µm absorbed by the water contained in the nodule cells, which causes their immediate vaporisation. The CO2 laser offers a relatively short healing time but can cause temporary redness and crusting in the days following the session. Moreover, it is important to limit sun exposure after the treatment and to use daily sun protection, in order to prevent the risks of hyperpigmentation.

Some nodules may be indicators of malignant tumours. At the slightest doubt, do not hesitate to consult a dermatologist if you notice the presence of a lump under your skin.

• HANCOX J. & al. Diagnosis and Treatment of Acne. American Family Physician (2004).

• SHALITA A. & al. Therapeutic considerations for severe nodular acne. American journal of clinical dermatology (2011).

• TANGHETTI E. & al. The Role of Inflammation in the Pathology of Acne. Journal of Clinical and Aesthetic Dermatology (2013).

• BHUSHAN R. & al. Guidelines of care for the management of acne vulgaris. Journal of the American Academy of Dermatology (2016).

• TIDY C. Skin and subcutaneous nodules. Patient (2021).