Image 1-High power magnification showing lentigo-like changes.



Image 2 -The clinical photo shows the characteristic reticulate appearance of Dowling-Degos disease.

Case Study

This is a 27 year old female referred by her primary care provider for uation of persistent dryness and discoloration on the right pretibial area present for approximately 2 years. Cortisone cream was prescribed with minimal change. She now presents with an approximately 6 x 10-cm area of reticulate hypo and hyperpigmentation on the right pretibial area with 2 smaller adjacent areas.

The clinical assessment is discoid lupus erythematosus versus morphea.

Diagnosis:
Reticular Melanotic Hypermelanosis consistent with
Dowling-Degos Disease

Comment:

There are many times when the histopathologic changes are non-specific or do not appear to fit with the clinical diagnostic impression. This recent case illustrates these typical quandaries. The clinical impression was possible discoid lupus versus morphea. However, the review of the skin biopsy revealed only minimal epidermal changes resembling a lentigo.

The referring dermatologist was kind enough to submit a clinical photograph with his case (see Image 2). The reticulated pattern is striking. Combining the histopathology with this clinical finding, a diagnosis of a reticulate melanotic hypermelanotic disorder is favored. In this clinical setting, Dowling-Degos disease would be a likely diagnosis. There is usually onset in early adult life, equally affecting both sexes, and may be slowly progressive. The hyperpigmentation may begin in the axillae and groin and can spread to the intergluteal and inframammary folds, neck, trunk, and arms.

In our patient, a diagnosis of Reticulate Acropigmentation of Kitamura was definitely considered and indeed, there may be clinical overlap between the two disorders. In this latter disease, the reticulate changes usually initially involve the backs of the hands and then spread to other parts of the body. Onset may be during the 1-2nd decades. Palmer pits and epidermal breaks in the ridge pattern are commonly found.

The spectrum of reticulated melanotic disorders is vast and includes entities such as Reticulate Acropigmentation of Kitamura, Galli-Galli disease, dermatopathia pigmentosa reticularis, and dyskeratosis congenita.

Several recent papers have documented an unusual association with hidradenitis suppurativa, multiple epidermal inclusion cysts, cutaneous squamous cell carcinomas and Dowling-Degos disease (see reference below).

In summary, we were saved by the patient! The patient's clinical photograph prevented us from making an embarrassing and uninformed diagnosis. Thanks to the referring dermatologist for providing such a beautiful clinical photograph.

References:

The Doctor's Doctor-Reticulate Melanotic Hypermelanosis

Loo WJ, Rytina E, Todd PM.
Hidradenitis suppurativa, Dowling-Degos and multiple epidermal cysts: a new follicular occlusion triad. Clin Exp Dermatol. 2004 Nov;29(6):622-4

Wenzel J, Tappe K, Gerdsen R, Uerlich M, Philipp-Dormston W, Bieber T, Petrow W.
Successful treatment of Dowling-Degos disease with Er:YAG laser. Dermatol Surg. 2002 Aug;28(8):748-50.