Dermatologic Look-Alikes

Clinical presentation

Characteristic locations

Associations

• Firm pruritic nodular lesions, possibly with burning or stinging sensation

• Symmetric distribution usually on extensor surfaces

• Mental health disorders

• HIV

• Hematologic malignancies

• Diabetes

• Liver disease

• Thyroid disorders

• End-stage renal disease

• Atopic dermatitis

• Psoriasis

• Neurotic excoriation

Etiology

• Immune and neural dysregulation

• Any cause of itch including primary dermatologic conditions and systemic conditions

• Intensely pruritic hyperkeratotic plaques and nodules

• Shins, ankles, and interphalangeal joints in a symmetric distribution

• Hepatitis C

• Chronic inflammation

• Chronic venous insufficiency

Histology

• Orthohyperkeratosis

• Irregular epidermal hyperplasia

• Hypergranulosis

• Increased dermal fibroblasts and capillaries

• Sometimes increased nerve fiber density

• T-cell activation against basal keratinocytes

Diagnosis

Treatment

• History and physical examination

• First-line treatment: topical corticosteroids

• Systemic immunosuppressants for refractory cases

• Dupilumab is FDA approved for prurigo nodularis

FDA, Food and Drug Administration differentiating features between the conditions. Although hypertrophic LP and PN both show pearly, white areas on dermoscopy, the areas are more prominent and might possess a starburst appearance in PN.7 Comedo-like openings filled with yellow keratinous plugs are a sign of transepithelial elimination and are only seen in hypertrophic LP and not in PN.7 However, comedo-like openings are not specific for hypertrophic LP and are commonly seen in other skin lesions including seborrheic keratoses.7 Another dermoscopic feature seen in hypertrophic LP and not in PN are gray-blue globules, which are a sign of melanin incontinence that

• Epidermal hyperplasia

• Hypergranulosis

• Lamellated hyperkeratosis centered on follicular infundibula and acrosyringia

• Lichenoid lymphocytic infiltrate

• History and physical examination

• Punch biopsy is often helpful

• First-line treatment: topical corticosteroids

• Systemic immunosuppressants for refractory cases

• Cryotherapy results from vacuolar degeneration.7 Hypertrophic LP can also resemble squamous cell carcinoma or keratoacanthomas, but shin involvement and absence of lesions in sun-exposed areas can help make the diagnosis of hypertrophic LP.7 Close follow-up and biopsy for lesions that show rapid growth, ulceration, and bleeding are recommended.12

Treatment of hypertrophic LP is similar to the treatment of other variants of LP. Topical corticosteroids include first-line therapy.11 However, systemic steroids, mycophenolate mofetil, acitretin, hydroxychloroquine, cyclosporine, methotrexate, intralesional steroids, and cryotherapy, alone or in combination, have also shown success.11,12 Findings from recent studies suggest that enoxaparin is an effective alternative because it has anti-inflammatory properties, however, more work is needed to ascertain its efficacy.11 Without proper treatment, hypertrophic LP can persist for many years.6

The biopsy in this case revealed hyperkeratosis, hypergranulosis, epidermal hyperplasia, and lichenoid lymphocytic infiltrate. This patient was diagnosed with hypertrophic LP and was started on therapy with oral prednisone. ■

Rishabh Lohray is a medical student at Baylor College of Medicine in Houston,Texas, and an MBA student at Rice University.Talia Noorily, MD, is a dermatology resident at Baylor College of Medicine.

References

1. Huang AH, Williams KA, Kwatra SG. Prurigo nodularis. J Am Acad Dermatol. 2020;83(6):1559-1565.

2. Ständer S, Augustin M, Berger T, et al. Prevalence of prurigo nodularis in the United States of America: a retrospective database analysis. JAAD Int. 2021;2:28-30.

3. Williams KA, Huang AH, Belzberg M, Kwatra SG. Prurigo nodularis: pathogenesis and management. J Am Acad Dermatol. 2020;83(6):1567-1575.

4. Kwon CD, Khanna R, Williams KA, Kwatra MM, Kwatra SG. Diagnostic workup and evaluation of patients with prurigo nodularis. Medicines (Basel). 2019;6(4):97.

5. Vaidya DC, Schwartz RA. Prurigo nodularis: a benign dermatosis derived from a persistent pruritus. Acta dermatovenerol Croat. 2008;16(1):38-44.

6. Gorouhi F, Davari P, Fazel N. Cutaneous and mucosal lichen planus: a comprehensive review of clinical subtypes, risk factors, diagnosis, and prognosis. ScientificWorldJournal. 2014;2014:742826.

7. Ankad B, Beergouder S. Hypertrophic lichen planus versus prurigo nodularis: a dermoscopic perspective. Dermatol Pract Concept. 2016;6(2):9-15.

8. Welsh JP, Skvarka CB, Allen HB. A novel visual clue for the diagnosis of hypertrophic lichen planus. Arch Dermatol. 2006;142(7):954.

9. Schwager Z, Stern M, Cohen J, Femia A. Clinical epidemiology and treatment of lichen planus: a retrospective review of 2 tertiary care centers. J Am Acad Dermatol. 2019;81(6):1397-1399.

10. Goldstein B, Goldstein A, Mastow E. Lichen planus. UpToDate. Wolters Kluver; 2019.

11. Weston G, Payette M. Update on lichen planus and its clinical variants. Int J Womens Dermatol. 2015;1(3):140-149.

12. Guillen-Climent S, Porcar Saura S, Monteagudo C, Ramón Quiles MD. Hypertrophic lichen planus: importance of follow-up and clinicopathologic correlation. Actas Dermosifiliogr (Engl Ed). 2021;112(2):184-185.