Morphea simulating paucibacillary leprosy clinically and histopathologically.

Clinically and histopathologically paucibacillary leprosy shows similar features with initial morphea. In this case we report a 24 yr-old male patient who presented to our dermatology department with diagnosed paucibacillary leprosy by his local dermatologist, and confirmed by perineurovascular lymphocytic infiltrate in the histopathological exam. On physical examination we found new plaque lesions that were suggestive of morphea with alteration of sensitivity. A new biopsy was performed showing sclerotic superficial dermis with thickening of the collagen bundles in deep dermis and linear arrays lymphocytic infiltrate between the collagen bundles that confirm the diagnosis of morphea.

What was known?

Leprosy is a disease that shares some characteristics with multiple skin disorders; the early stage of morphea is one of those disorders with not only clinical but also histopathological similarity.

Introduction

Through the history, the true diagnosis of leprosy has always been a challenge, not only for the multiple diseases that shares some clinical features but also because the similarity of a few in the histopatological aspect. We report in here a case of morphea showing very similar characteristics in the clinical and histopatological findings with paucibacillary leprosy, we also discuss the different aspects between the two entities and finally we focus in an atypical pattern of infiltration in morphea.

Case Report

A 24 yr-old male presented to our dermatology department complaining of hypochromic plaques in his abdomen and neck.

In November of 2009, he consulted for a solitary oval hypochromic plaque with reddish-edge and smooth surface in the abdomen with absent of hair inside the plaque [Figure 1].

Figure 1

Oval hypocromic plaque with lilac-edge and smooth surface in the abdomen with absent of hair inside the plaque. Notice the scar of the first biopsy done from the edge of the lesion

A biopsy was performed in the edge of the lesion under suspicion of paucibacillary leprosy. The result of the biopsy showed perineurovascular lymphocytic infiltration [Figure 2]. A bacilloscopy was performed with negative result.

Figure 2

Perineurovascular and intersticial infiltrate predominantly lymphocytic, with linear arrays between the collagen bundles (H and E, ×100)

The patient was diagnosed with paucibacillary leprosy and treatment was established.

The patient received treatment for five months with rifampicin 600 mg/monthly and dapsone 100 mg/daily without improvement. In the fifth month of treatment the patient developed a satellite lesion with similar characteristics and another plaque with the same morphology in the neck, reason that made him consult again.

On physical examination the main lesion was an oval indurated hypochromic plaque with reddish-edge and smooth surface in the abdomen with some hairless areas inside the plaque and no alteration of sensibility. In the upper part of the main lesion there was a smaller hypocromic plaque with lilac-colored edge and no hair inside, did not have alteration of sensibility either; in the neck there was another hypochromic plaque with light erythematous edge and scaly surface with alteration of sensibility.

A new biopsy from the center of the initial plaque was performed suspecting localized morphea. The result showed subepidermic hyalinized collagen with loss of epidermal rete ridge pattern and some dilated superficial venules in the superficial dermis; there was atrophy of the adnexal structures. In the middle dermis there was a lymphocytic infiltrate with linear arrays between the thickened collagen bundles that enclose some ducts and eccrine glands [Figure 3].

Figure 3

There is a hyalinized superficial dermis with thickened collangen bundles in the mid and deep reticular dermis; notice the absence of adnexal structures (H and E, ×100)

Those findings in the histopatological exam confirmed the diagnosis of morphea.

Discussion

Morpheae is a disorder of unknown cause in which there is localized sclerosis of the skin.[1] The etiology appears to be involved with the fibroblastic cells in which alterations in the grow factors (platelet-derived growth factor)[2] and receptor expression (TGF-β)[3] have been reported in in-vitro studies. Those alterations appear to lead to increased connective tissue growth factor (CTGF) gene expression and finally fibrosis.[45] Immunological cytokines, auto-immune, trauma, immobility, radiotherapy, hormonal and infection etiology mainly with Borrelia burgdorferi also have been reported.[6]

Clinically the plaque lesions are indurated purplish or mauve in color. After some months they become thickened and and a characteristic lilac-colored edge develops. Frequently they present diminished sensibility and they can be bilateral multiple and asymmetric.[16]

Histopathological features depend the stage of the lesion and the site of the biopsy. Biopsies done in the periphery of the lesion will show markedly lymphocytic and histiocytic inflammatory infiltrate scattered in the middle dermis. In the lower part of the dermis and subcutaneous tissue, it begins to appear as broadening of the collagen bundles with diminished interbundle spaces.[67]

When the disease progresses, the inflammatory infiltrate slowly starts to disappear and is replaced by hyalinized connective tissue. The atrophic adnexal structures diminish in number until they disappear.[6-9] The sweat glands generally are located in the middle of the sclerotic collagen bundles in the middle and deep dermis.[68]

In Brazil, leprosy is a frequent infectious disease and is first impression differential diagnosis in several diseases.

Clinically patients with leprosy can be in two opposite sides, the paucibacillary (1-5 lesions) or the multibacillary (more the 5 lesions) subtype, reflective of the host immune response; the paucibacillary subtype is characterized by a predominantly Th1 cell-mediated immune response and the multibacillary subtype is characterized by a predominantly Th2 humoral response.[10]

The paucibacillary subtype is composed by the initial indeterminate leprosy and the tuberculoid leprosy.[11] The initial indeterminate lesions consist of hypopigmented macules with not well defined borders, generally without involving hair growth and nerve function.[12] In the histopathological findings there is a perineurovascular and adnexal non-specific infiltrate composed predominantly of lymphocytes.[13]

Tuberculoid lesions present as a plaque that is frequently solitary, with central hypopigmentation and raised erythematosus edge, the surface is sometimes scaly hairless and with alteration of sensibility.[1112] In the histopathological exam it presents with non-caseating granulomas composed of epitheliod cells, lymphocytes and Langhans cells.[13]

In our case the initial histopathological findings showing non- specific perineurovascular infiltrate directed to the diagnosis of paucibacillary leprosy. In the literature review there was no evidence of such pattern of infiltration in morphea but with the lack of response to the treatment and the appearance of new lesions the diagnosis of morphea became more likely.

It was interesting to note the localization of the lymphocytic infiltrate around the nerve and the linear disposition of the lymphocytes that haven’t been reported until now. We suggest this could be another pattern of infiltration in morphea and there should be new studies to confirm this theory.

What is new?

The Perineural infiltration with linear array of lymphocytes in the histopathological examination could be an initial pattern of morphea.