Indian Journal of Paediatric Dermatology

: 2019  |  Volume : 20  |  Issue : 3  |  Page : 261--266

Hyperpigmented patches following blaschko lines: Two probable cases of linear atrophoderma of moulin with subtle atrophy and a critical review of the subject

Tasleem Arif1, Mohammad Adil2, Marwa Sami1, Noora Saeed3,  
1 Ellahi Medicare Clinic, Srinagar, Kashmir, India
2 Department of Dermatology, Jawaharlal Nehru Medical College, Aligarh Muslim University, Aligarh, Uttar Pradesh, India
3 Department of Pathology, Jawaharlal Nehru Medical College, Aligarh Muslim University, Aligarh, Uttar Pradesh, India

Correspondence Address:
Dr. Tasleem Arif
New Colony Soura, Near Water Supply Control Room, Srinagar - 190 011, Kashmir


Linear atrophoderma of Moulin (LAM) is a rare clinical entity characterized by hyperpigmented, depressed band-like skin lesions following blaschko lines (BL). Since its first description by Moulin et al., several authors have presented cases with variable clinical and histopathological features and have diagnosed them as LAM. Whether all those cases represented classical LAM as described by Moulin et al. or they represented a related dermatosis; depends on whether we confine the diagnosis of LAM as presented by Moulin et al. or consider it to be a spectrum where lesions may have overlapping clinical and histopathological findings. Some dermatoses that follow BL and have overlapping clinical and histopathological findings include LAM, idiopathic atrophoderma of Pasini and Pierini and Blaschkolinear morphea. Thus, it becomes difficult for a physician to diagnose these conditions when their typical clinical and histopathological findings are not present, especially when they present in early stages of evolution. Here in, we present two cases of LAM where the visible clinical atrophy is mild in one and not appreciable in the other. Whether our cases are the genuine cases of LAM or represent a stage of LAM or fall in the spectrum of LAM depends on how we expand the definition of LAM. We believe that whenever there is an encounter with hyperpigmented lesions in a blaschkoid pattern, a long-term follow-up is needed with serial biopsies to make a final definitive diagnosis.

How to cite this article:
Arif T, Adil M, Sami M, Saeed N. Hyperpigmented patches following blaschko lines: Two probable cases of linear atrophoderma of moulin with subtle atrophy and a critical review of the subject.Indian J Paediatr Dermatol 2019;20:261-266

How to cite this URL:
Arif T, Adil M, Sami M, Saeed N. Hyperpigmented patches following blaschko lines: Two probable cases of linear atrophoderma of moulin with subtle atrophy and a critical review of the subject. Indian J Paediatr Dermatol [serial online] 2019 [cited 2019 Sep 22 ];20:261-266
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Full Text


Linear atrophoderma of Moulin (LAM) is a rare dermatologic disorder which is characterized by hyperpigmented depressed plaques following blaschko lines (BL). Originally described by Moulin et al., the lesions classically develop without an apparent preceding inflammatory phase, and remain stable, without response to treatment.[1] Although dermal atrophy has not been demonstrated histologically, use of ultrasound probes to determine skin thickness has shown that there is thinning of the subcutaneous tissue underlying the lesions of LAM. Thus, the clinical appearance of atrophy is due to a decrease in subcutaneous tissue.[2] There exist many similarities between the dermatoses that follow BL and having similar histopathological findings. These include LAM, idiopathic atrophoderma of Pasini and Pierini (IAPP), and blaschkolinear morphea. Whether LAM represents a part of a disease spectrum or it is a single entity is also a topic of debate. IAPP is characterized by hyperpigmented depressed plaques with cliff drop borders similar in appearance to LAM, but IAPP generally does not follow the lines of blaschko. Many authors have considered IAPP to be a superficial abortive form of morphea in which induration fails to develop.[3] On the other hand, morphea itself has several variants including linear, plaque, generalized, and deep forms, all characterized by excessive collagen deposition in the dermis or underlying tissues at some stage of the disease. Hyalinized thickened and clumped dermal collagen has also been reported in cases of LAM and IAPP thus making it very difficult for a physician to differentiate between morphea, IAPP, and LAM, especially when the typical clinical and histopathological findings are not present.[4]

In the original description of LAM, there was only basal layer hyperpigmentation while other epidermal layers and dermis were normal including the normal appearing dermal collagen and elastin.[1] However, in the subsequent years, the clinical and histopathological criteria for the diagnosis of LAM have been widely expanded and cases with varying clinical and histopathological findings have been classified under the same umbrella of LAM.[4],[5] This has led to more confusion in diagnosing LAM and differentiating between these three disease entities when they present in a blaschkoid pattern. In this article, we are reporting two cases where the hyperpigmented patches are present along BL; however in one case, clinical atrophy is subtle while in the other, we could not appreciate atrophy on examination. Whether our cases represent the genuine cases of LAM depends on how willing we are to expand the definition of LAM; whether we restrict it to the entity as defined by Moulin et al. or consider it as a spectrum with variable clinical and histopathological features. The clinical and histopathological features of our cases fit most closely to the diagnosis of LAM though we have tried to rule out other related dermatoses that can follow BL.

 Case Reports

Case 1

A 22-year-old male patient complained of linear nonitchy pigmented lesions over the left leg that started initially over the left popliteal fossa and progressed upward to the thigh and downward to the ankle. There was no history of erythema, hardening of the skin or violaceous border surrounding the lesions. The patient denied any history of trauma or skin lesions before the complaints. There was no history of similar lesions in any of the family members. On examination, a linear band comprising multiple brownish-colored patches were observed extending from just below the left gluteal crease to the middle of the popliteal fossa [Figure 1] and then to the lateral aspect of the calf reaching up to the ankle. On palpation, mild atrophy was appreciated at some places in the lesions. There were no signs of induration or inflammation. Rest of the dermatological and systemic examination was normal. Laboratory investigations including anti-nuclear antibody were normal or within the normal limits. A 5-mm punch skin biopsy for histopathological examination revealed a normal epidermis except for increased pigmentation of the basal layer with sparse dermal inflammatory infiltrate. There was mild thickening of collagen bundles in the dermis [Figure 2]. Skin appendages including sweat glands were intact. The subcutaneous tissue layer was not commented on by the histopathologist probably because the biopsy was a punch biopsy and lacked a full-thickness subcutaneous tissue layer.{Figure 1}{Figure 2}

Case 2

A 34-year-old female patient presented to us with an 8 months history of asymptomatic linear hyperpigmented lesions over the left lower abdomen, thigh, and leg. The lesions started from the left lower abdomen and then progressed to ipsilateral thigh and leg reaching up to the ankle. There was no history of trauma or any skin lesions before this. The patient denied any history of erythema, hardening, or violaceous border surrounding the lesions. There was no history of similar disease in the family. On examination, there were multiple hyperpigmented patches in a linear band-like distribution observed extending from the left lower abdomen, medial aspect of the left thigh and leg and reaching up to the medial malleolus [Figure 3]. We could not appreciate atrophy on palpation. No signs of induration or inflammation were noted. Rest of the dermatological and systemic examination was unremarkable. Laboratory investigations including anti-nuclear antibody were unremarkable. Histopathology from the 5-mm punch skin biopsy showed normal epidermis, basal layer pigmentation, and thickened dermis filled with collagen [Figure 4]. However, the appendages were intact. There was no mention of the subcutaneous tissue layer for the reasons already explained in case 1.{Figure 3}{Figure 4}


LAM is a rare cutaneous disorder which was first described by Moulin et al. in 1992. They reported five healthy young patients who had unilateral hyperpigmented depressed plaques along BL on the trunk and extremities without any evidence of long-term progression. There was no inflammation, induration, or sclerosis associated with the plaques.[1],[6] The characteristic histopathological finding was hyperpigmentation of basal layer, whereas other epidermal layers and the dermis including collagen and elastin was unremarkable.[1],[5],[6] Hence, the clinical atrophy was related to the loss of subcutaneous tissue; however, a deep biopsy from both the affected skin and contralateral sides was originally not performed to assess the thickness of subcutaneous tissue. Moulin et al. suggested the term “blaschkose” in contrast to the term “blaschkitis.”[1] Two years later, in 1994, it was Bauman et al. who reported a patient with a similar disease that was published in a German journal and proposed the term Linear atrophoderma of Moulin.[7] However this term is a misnomer as there is no atrophoderma, the atrophy in LAM has been attributed to the thinning of subcutaneous tissue rather than dermis as discussed earlier. The diagnostic criteria[8] for LAM are summarized in [Table 1]. Bauman et al. classified the LAM as belonging to the group of acquired linear dermatoses following BL and believed that LAM is a variant of IAPP.[7] However, in recent years, the clinical and histopathological criteria of LAM have been expanded and not confined to what are mentioned in [Table 1]. Many authors have come up with cases of LAM with different clinical and histopathological findings not complying with the original diagnostic criteria.[4],[5]{Table 1}

LAM is a rare disease, and we could search some 40 cases in the literature. These also include such cases with different clinical and histopathological findings such as telangiectases, preceding inflammation, collagen sclerosis, and psoriasiform changes.[8],[9] As a result of these variable clinical and histopathological differences, the true number of cases may be actually smaller.[5],[6],[8] Hence, some authors proposed atypical variants of LAM while others presumed that different disease entities were categorized as LAM.[8],[9],[10] Brown and Fisherdescribed a case with preceding inflammation and they proposed that LAM has two variants, an inflammatory one, and the noninflammatory type. They believed that the initial inflammatory phase ultimately might lead to hyperpigmentation with atrophy.[11] Similarly, we can also presume that our cases are in the initial pigmentary phase which can later develop overt clinical atrophy. Utikal et al. reported two patients having linear atrophoderma with prominent telangiectatic erythema and argued that these cases might present a novel variety of LAM or a separate disease entity.[10] As per the diagnostic criteria, LAM starts in childhood or adolescence; we could find a congenital case involving leg and two cases where the onset of the atrophoderma was after 30 years challenging the original diagnostic criteria.[6],[12],[13] Classically, Moulin et al. had suggested unilateral localization of lesions in LAM, however, after literature search, we could find five cases where lesions were present bilaterally.[4],[10],[11],[14],[15] LAM involves trunk or limbs as has been proposed, but there are reports where LAM involved the neck.[9],[16] Apart from this, there are case reports where not only hyperpigmented but also hypopigmented plaques were also observed in association with lentiginosis in LAM.[14],[15],[17] From this discussion, it is clear that the original criteria did not cover all the cases of LAM which have been reported so far. This means that either we have to expand the definition of LAM to incorporate all those cases with regard to clinical and histopathological features or we have to consider alternative diagnoses for those cases which did not meet the original criteria. Our cases met all the criteria of LAM except the clinically evident atrophy which was subtle in one case and in the other it was not appreciated. We postulate that early lesions may be hyperpigmented and later develop visible clinical atrophy.

The histopathology of LAM has been a topic of debate. In the original case series by Moulin et al., there was only basal layer hyperpigmentation, whereas the rest of the epidermal layers and dermis was normal.[1] However, new histopathological findings have been reported by other authors that include perivascular lymphocytic infiltrates, epidermal atrophy, decreased elastic tissue, altered dermal collagen, dermal atrophy, acanthosis, plasma cell infiltrate, and dilated dermal blood vessels.[4] Surprisingly, the most common finding that has been described in LAM is a perivascular lymphocytic inflammatory infiltrate in the superficial dermis combined with abnormal collagen fibers.[8] Since these cases presented sufficient clinical evidence to support a diagnosis of LAM, they suggested that LAM was not as limited in scope as has been described originally but probably comprised a wider set of clinical and histopathological features that fit rather within a spectrum of related disorders.[4] Thus, we believe that there is a need of consensus on the diagnostic criteria of LAM. We are of the opinion that new diagnostic criteria with wider clinical and histopathological spectrum should be framed to account for all the clinical and histopathological differences in cases of LAM.

The pathogenesis of LAM is not clear. Danarti et al. have proposed that LAM may reflect the action of an autosomal lethal gene surviving by mosaicism. Mosaicism is defined as the presence of two or more genetically distinct cell populations in an individual derived from a single zygote.[12] Utikal et al. suggested that a secondary event (probably environmental) could affect these mutated cells, leading to the clinical manifestation of the disease.[10] No triggering factor has been clearly identified so far. In one adult case of LAM, the authors suspected exposure of sun in collaboration with parasiticide substances and tomato plants as potential environmental factors inducing the clinical manifestation.[13]

The differential diagnosis in our cases includes some related disorders where the lesions are present in blaschkoid distribution with histopathology showing basal hyperpigmentation with altered collagen in the dermis. IAPP is differentiated by the characteristic atrophic plaques with cliff drop borders, usually in a bilateral distribution.[18] It rarely occurs along BL, and the atrophy in IAPP has been attributed to the loss of dermal tissue.[19] Morphea usually has an initial inflammatory phase, and the plaques have lilac colored rings. Induration and sclerosis on histopathology is the hallmark of morphea. The prognosis of morphea is less favorable and can lead to complications in contrast to LAM.[20],[21] Blaschkoid lichen planus (LP) can also be considered as differential when the atrophy is not well established. However, pruritic nature of the lesions and the histopathology suggestive of LP easily differentiates it from LAM.[22] Linear and whorled nevoid hypermelanosis can be differentiated by its early onset at birth or soon after birth and absence of atrophy in the lesions. Linear postinflammatory hyperpigmentation was ruled out since there was no history of any preceding dermatosis. The summary of major differential diagnoses of LAM has been mentioned in [Table 2]. Our cases did not fall in any of the available differentials. However, keeping in mind the clinical characteristics and histopathological findings, our cases were near the diagnosis of LAM as no other alternative diagnosis could match such features.{Table 2}

It is always difficult to investigate the thickness of subcutaneous tissue layer as it is easily missed in most of the routine skin biopsies. To assess the subcutaneous tissue, the skin biopsy, preferably an elliptical one deep enough to reach the fascia to measure the entire thickness of the subcutaneous tissue layer should be taken. Second, a control sample biopsy from the contralateral side is advised. Hence, the correct way of taking a skin biopsy should consider the depth of biopsy specimen, somatic features of the patient (age, sex, and skin color), stage of the disease, the dermatological history of the patient and follow up, and the area of the body from which skin biopsy has been taken, for example, dermal collagen bundles are normally thickened in the back and thinned in the folds.[21] In addition, an ultrasound assessment of the skin should also be done to account for the thickness of dermis and subcutaneous tissue layer as has been carried out by various authors in the workup of their cases.[21]

There is no definitive treatment of LAM. In general, LAM is generally a self-limiting disease with a favorable prognosis in contrast to linear morphea. Progression of the lesions usually stops within a few months without any internal organ involvement.[23] Various treatment modalities have been tried for LAM but with disappointing results. These include oral potassium aminobenzoate, weekly methotrexate (20 mg/week), topical corticosteroids and heparin, phototherapy, intravenous penicillin, a combination of psoralen plus ultraviolet A and penicillin; association of high-dose Vitamin E (400 IU/day) and topical clobetasol propionate. Since the problem is mainly esthetic, some authors have tried a self-tanning cream on a 15-year-old girl which led to homogenization of the skin pigmentation.[24],[25]


From various aspects, our cases appear to be similar to the LAM except for lack of atrophy in one case and subtle atrophy in the other. However, whether our cases represent genuine cases of LAM depends upon how willing we are to expand the diagnostic criteria of LAM. Second, it also depends upon whether we consider LAM as a distinct entity or as a spectrum of an evolving dermatosis evaluated in different stages. Third, we could not find any alternative diagnosis which can nearly match the clinical and histopathological findings of our cases. Finally, it is also possible that our cases are in the initial pigmentary stage of the disease and on further progression may develop overt atrophy. Thus, we are of this opinion that only long-term follow-up and serial biopsies can make the definitive diagnosis of such cases.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given his/her consent for his/her images and other clinical information to be reported in the journal. The patient understands that name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.


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