Lichenoid and granulomatous dermatitis: Points to ponder
By Kiran Motaparthi, MD
June 10, 2020
Vol. 2, No. 23
In Lichenoid granulomatous dermatitis revisited: a retrospective series, Braswell et al. studied an unusual reaction pattern with confounding features. (1) The authors observed that while TH1 cells are the primary subset involved in lichenoid interface dermatitis, TH2 cells can also activate cytotoxic CD8 T cells. Additionally, some antigens can trigger TH1 responses and simultaneously activate CD4 T cells. (2, 3, 4) Concomitant TH1 and TH2 responses drive the vacuolar change and macrophage recruitment observed in lichenoid granulomatous dermatitis (LGD). Previously, dermatopathologists relied on descriptive reports to communicate these features, and dermatologists found clinical correlation of LGD challenging. In the largest series of LGD to date, Braswell et al. identified drug eruption (see image) and lichenoid keratosis as the most common clinical diagnoses associated with LGD, followed by tattoo reaction, postherpetic dermatitis, and scabies or postscabietic dermatitis. Pigmented purpuric dermatitis (PPD) and lichen striatus were also observed. (1)
Along with drugs, infectious agents can also serve as antigens that provoke concomitant TH1 and TH2 responses. Prior studies observed Mycobacterium leprae, Mycobacterium tuberculosis, and fungi in skin biopsies with LGD. Secondary syphilis may feature lichenoid, psoriasiform, and granulomatous reaction patterns. LGD is not limited to active infections: id reactions to varicella zoster virus and Epstein-Barr virus have also been described. (5) The author has observed a case of tuberculid LGD in a patient with underlying pulmonary tuberculosis but without identifiable acid-fast bacilli or Mycobacterium tuberculosis DNA in the skin. However, in Lichenoid granulomatous dermatitis revisited, associated infections were not identified by histologic or clinical history. This difference arose due to methodology: the authors sought cases of LGD for study inclusion based on descriptive report rather than by diagnosis and then screened for infectious agents prior to clinical correlation. In the archives queried, infections were likely reported without the descriptive terminology of LGD. (1) Similarly, cutaneous T-cell lymphoma (CTCL) has been described as LGD previously (5, 6, 7) but was not identified in this study. As a result, the findings by Braswell et al. are practical and readily applicable. When confronted by the LGD pattern, dermatopathologists should consider CTCL or exclude infections due to fungi, mycobacteria, and Treponema pallidum, depending on the clinical context. Subsequently, morphologic clues allow dermatopathologists to provide a more concise differential diagnosis. Eosinophils and psoriasiform epidermal changes favor drug eruption, perineural and perifollicular inflammation point to tattoo reaction or postherpetic dermatitis, and red blood cell extravasation suggests PPD. (1)
Point to Remember: Although lichenoid granulomatous dermatitis is an uncommon histologic pattern, the majority of associated clinical diagnoses are common, notably drug eruption and lichenoid keratosis, and can be suggested based on histologic features. Depending on the clinical context, cutaneous T-cell lymphoma or fungal, mycobacterial, and spirochetal infections may require exclusion.
Our editor's viewpoint
Warren R. Heymann, MD
Diagnostic pearls learned during training become permanently embedded in our cerebral cortex, influencing practice over an entire career. As a dermatopathology fellow, I was taught to always consider two crucial diagnoses when observing a lichenoid and granulomatous dermatitis — syphilis and cutaneous T-cell lymphoma. In this commentary, Dr. Motaparthi reviews the literature on the implications of a lichenoid and granulomatous dermatitis. Although I will always think of syphilis and cutaneous T cell lymphoma — so those diagnoses are not missed — when reporting such cases, I now know that this histologic pattern is more likely to reflect a drug eruption in the right context. The bottom line is that a histologic diagnosis of lichenoid and granulomatous dermatitis is not a diagnosis, but rather a morphologic description, mandating communication between the clinician and dermatopathologist to reach the proper diagnosis.
Braswell DS, Hakeem A, Walker A, Sokumbi O, et al. Lichenoid granulomatous dermatitis revisited: a retrospective case series. J Amer Acad Dermatol. 2019 Aug 1. pii: S0190-9622(19)30967-3. doi: 10.1016/j.jaad.2019.05.100. [Epub ahead of print]
Magro CM, Crowson AN. A distinctive cutaneous reaction pattern indicative of infection by reactive arthropathy associated microbial pathogens: the superantigen ID reaction. J Cutan Pathol. 1998;25:538-544.
Sontheimer RD. Lichenoid tissue reaction/interface dermatitis: clinical and histological perspectives. J Invest Dermatol. 2009; 129(5):1088-1099.
Mosmann TR, Sad S. The expanding universe of T-cell subsets: Th1, Th2 and more. Immunol Today. 1996;17:138-146.
Magro CM, Crowson AN. Lichenoid and granulomatous dermatitis. Int J Dermatol. 2000;39:126-133.
Garrido MC, Maroñas-Jimenez L, Ortiz PL, Rodriguez-Peralto JL. Lichenoid granulomatous mycosis fungoides. Am J Dermatopathol. 2017;39:614-617.
Belousova IE, Khairutdinov VR, Bessalova A, Kazakov DV. Mycosis fungoides manifesting as giant cell lichenoid dermatitis. Am J Dermatopathol. 2018;40:283-285.
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