Shades of Gray

Presented by Makayla Powers, PA-C

The patient is a 55 yo woman who presents with a six month history of hyperpigmentation on the presternal area, the right axilla, the posterior neck and the mid lower back.  It was initially thought to be CARP (Confluent and Reticulated Papillomatosis) and she was treated with doxycycline.  After one month of therapy there was no improvement.

O/E: Well-defined tan patches presternal.  More grayish areas on posterior neck and back.  Small hyperpigmneted macules in the right axilla.

Pathology: Courtesy of David Jones, M.D., Dermatopathologist, Berkshire Medical Center

The low power image shows a sparse but appreciable lichenoid and interface dermatitis that involves the papillary dermis and extends down the follicular elements. Higher power images identify the extensive pigment incontinence with melanophage that are associated with colloid/cytoid bodies. The vacuolar changes are best represented on the high power images that highlight rare dead and dying keratinocytes in the lower third of the epidermis. A pancytokeratin stain cross reacts with the colloid bodies as can be seen on macular amyloidosis.

Pancytokeratin Stain

The histological differential diagnosis for this pattern is fairly extensive and would require a distinct clinico-pathologic evaluation. Histologic differentials include but are not limited to non-specific post inflammatory pigment alteration, a fixed drug eruption, macular amyloidosis, Eryhtema dyschromicum perstans (EDP), and lichen planus pigementosum (LPP). 

The lack of a thick granular layer bodes against a true atrophic lichen planus or lichen planus pigmentosum. The lack of a deep dermal pigmentation makes ashy dermatosis less likely.

Discussion: Based on clinicopathological correlation, we favor Lichen planus pigmsntosum versus ashy dermatitis (EDP).  We are not confident that we can be more specific.  She was on no medications that could have contributed.  Since neither of these entities are predictably amenable to therapy and can improve over time, we are going to temporize and follow the patient in a few months. She is not eager for treatment at this time.

We welcome your comments.  Please send them to djelpern@gmail.com and they will be posted. 

References: 

1. Ashy Dermatosis and Lichen Planus Pigmentosus: The Histopathological Differences. Rutnin S, Udompanich S, Pratumchart N, Harnchoowong S, Vachiramon V. Biomed Res Int. 2019 Oct 28;2019:5829185. doi: 10.1155/2019/5829185. eCollection 2019. PMID: 31781623. Free PMC article.

2. Kumarasinghe SPW, et. al.  A global consensus statement on ashy dermatosis, erythema dyschromicum perstans, lichen planus pigmentosus, idiopathic eruptive macular pigmentation, and Riehl's melanosis. Int J Dermatol. 2019 Mar;58(3):263-272.
Abstract: Ashy dermatosis (AD), lichen planus pigmentosus (LPP), erythema dyschromicum perstans (EDP), and idiopathic eruptive macular pigmentation are several acquired macular hyperpigmentation disorders of uncertain etiology described in literature. Most of the published studies on these disorders are not exactly comparable, as there are no clear definitions and different regions in the world describe similar conditions under different names. A consensus on the terminology of various morphologies of acquired macular pigmentation of uncertain etiology was a long-felt need. Several meetings of pigmentary disorders experts were held to address this problem. A consensus was reached after several meetings and collation of e-mailed questionnaire responses and e-mail communications among the authors of publications on the above conditions. This was achieved by a global consensus forum on AD, LPP, and EDP, established after the 22nd International Pigment Cell Conference held in Singapore in 2014. Thirty-nine experts representing 18 countries participated in the deliberations. The main focus of the deliberations was terminology of the conditions; as such, we present here the consensus statement of the forum and briefly review the available literature on the subject. We have not attempted to discuss treatment modalities in detail.

3. Albert Wu, Sachin Vaidya.  Literature Review of Treatment Outcomes for Lichen Planus Pigmentosus, Erythema Dyschromicum Perstans, and Ashy Dermatosis. J Cutan Med Surg. 2018 Nov/Dec;22(6):643-645.  The conclusion was that there are not good treatments for either of these.

We asked OpenEvidence how to differentiate between Lichen planus pigmentosis and ashy dermatitis (erythema dyschromicum perstans and the answer was that it is difficult.  Also, no practical suggestions were forthcoming regarding a likely therapy.  Here is a link to the OE report.