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Table of Contents
Year : 2019  |  Volume : 37  |  Issue : 3  |  Page : 178-179

Acquired penile smooth-muscle hamartoma with positive pseudo-Darier's sign

1 Department of Dermatology, National Taiwan University Hospital, Taipei, Taiwan
2 Department of Dermatology, China Medical University Hospital, Taichung, Taiwan

Date of Web Publication24-May-2019

Correspondence Address:
Dr. Tsen-Fang Tsai
Department of Dermatology, National Taiwan University Hospital, 7 Chung-Shan South Road, Taipei, 100
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ds.ds_49_18

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How to cite this article:
Chen SL, Tsai TF, Chou WY. Acquired penile smooth-muscle hamartoma with positive pseudo-Darier's sign. Dermatol Sin 2019;37:178-9

How to cite this URL:
Chen SL, Tsai TF, Chou WY. Acquired penile smooth-muscle hamartoma with positive pseudo-Darier's sign. Dermatol Sin [serial online] 2019 [cited 2023 Feb 4];37:178-9. Available from: https://www.dermsinica.org/text.asp?2019/37/3/178/259104

Dear Editor,

Smooth-muscle hamartoma (SMH) usually manifests as patches or mildly indurated plaques with or without hyperpigmentation, with overt overlying hair or with perifollicular papules without prominent hair. Variably orientated, increased smooth-muscle bundles are seen histologically in the dermis in sections. Hamartomas are defined as an abnormal malformation that resembles a neoplasm in the tissue of origin. They rarely affect the genitalia and are generally present at birth.[1] Acquired forms (ASMH) are rare, with <20 cases reported between the ages of 14 and 70 years, which commonly affected the forearm, neck, breast, and genital regions. Acquired scrotal SMH is even rarer with <10 documented cases.[2] Here, we describe a case of ASMH presenting as a solitary plaque with positive pseudo-Darier's sign in the penile region.

A 41-year-old previously healthy male presented with a 1-year history of an asymptomatic erythematous colored indurated plaque on the distal dorsal penile shaft [Figure 1]. The plaque was initially mildly indurated and itching; subsequently, it progressively enlarged. The patient denied any previous allergic reaction, trauma, or insect bites at the site of the lesion. Pseudo-Darier's sign was positive, but the laboratory data were nonspecific. The patient underwent total excision of the tumor without recurrence during 1-year follow-up. The histopathology showed disorganized, intersecting bundles of smooth muscle with vacuolated cytoplasm and cigar-shaped nuclei in a well-defined, scatter pattern in the dermis [Figure 2]a. No overlying basal hyperpigmentation, hair follicles, epidermal changes, or concentric layers that merged with the muscular stroma were noted, therefore excluding the diagnosis of Becker's nevus and angioleiomyomas. Nonspecific perivascular lymphocyte infiltrate was noted. The positive Masson's trichrome [Figure 2]b and smooth muscle actin stain [Figure 2]c supported the smooth muscle nature of the proliferation.
Figure 1: An asymptomatic erythematous and flesh-colored indurated plaque on the distal dorsal penile shaft

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Figure 2: (a) Disorganized, intersecting bundles of smooth muscle with vacuolated cytoplasm and cigar-shaped nuclei in a well-defined, scattered pattern in the dermis. There was no mitotic activity, hyperpigmentation, hair follicles, changes in epidermis, or concentric layers that merged with the muscular stroma. Nonspecific perivascular lymphocyte infiltrate was also noted (H and E). The tumor masses stained positive with trichrome in red (b) and smooth muscle actin (c), which supported the smooth muscle nature of the proliferation

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ASMHs involving the penile area were previously reported in only two cases: one with penoscrotal ASMH with the manifestation of thickening and swelling flesh in the scrotum and the entire penile shaft circumferentially [3] and the other presented with an igloo-like prepuce that completely covered the glans and resulted in phimosis.[1] Our case is unique because the plaque shape was not circumferential in shape. Pseudo-Darier's sign (transient piloerection or induration after rubbing or cold exposure) was negative in reported genital ASMH cases. In contrast, pseudo-Darier's sign is often positive in congenital SMH, and its intensity diminishes with age.[4],[5] Our patient, at the age of 41-year-old, still showed a positive pseudo-Darier's sign. SMH and scabies infection are the two main differential diagnosis of pseudo-Darier's sign. Moreover, the major differential diagnosis of Darier's sign including cutaneous mastocytosis, urticaria pigmentosa, and mastocytoma. The α-smooth muscle actin, trichrome, and desmin immunohistochemical positivity confirm the muscular histological origin.[2],[4] No evidence of scabies or increased mast cell infiltration was found.

The scrotal dartos is in continuation with the penile dartos and the anterior rectus muscle.[4] The origin of genital SMH is believed to be the tunica dartos in the scrotum, penis, and prepuce.[1],[2],[4] The penile dartos is composed of a discontinuous layer of smooth muscle fibers; some of them end at the balanopreputial sulcus while others extended further into the preputial dartos. This produces genital structure retraction when the external temperature decreases.[6]

Smooth-muscle proliferations of the skin and subcutis are classified based on their presumed origin, including the adnexal smooth muscle (pilar leiomyomas), vascular smooth muscle (angioleiomyoma), dartoic, muscularis mamillae, and areolar smooth muscle (genital leiomyomas). The other category includes hamartomas, such as those in association with epidermal nevi (Becker's nevus) and congenital and ASMHs.[4] Leiomyomas are ill-defined and tightly interlaced, while SMHs are well defined by a scattered pattern.[7] Angioleiomyomas have not been reported in the scrotum. They are sharply demarcated nodules that contain thick-walled blood vessels and are surrounded by a pseudocapsule of compressed fibrous tissue. The smooth-muscle fibers are in concentric layers with focal mucinous changes. Becker's nevus is a well-defined, hyperpigmented plaque that occurs in the second decade of life. It is a pilosebaceous hamartoma with large, deep-seated terminal hair follicles sometimes associated with hyperplastic pilar smooth muscle. Its epidermal surface is hyperkeratotic, acanthotic, and papillomatous with prominent basal hyperpigmentation.[4]

There is no known associated systemic involvement or malignant transformation in SMH.[8] Treatment is not necessary for ordinary congenital SMH. Surgery or laser therapy could be performed for cosmetic concerns or before the hamartoma causes psychological damage or affects sexual activity.[1],[5]

To our knowledge, this is the first case of ASMH presenting as a solitary plaque with a positive pseudo-Darier's sign in the penile region. We believe that the origin of genital SMH was in the tunica dartos of the penis.

Declaration of patient consent

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

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Conflicts of interest

There are no conflicts of interest.

  References Top

Sbano P, Sbano E, Alessandrini C, Criscuolo M, Fimiani M. Igloo-like prepuce: A peculiar aspect of smooth-muscle hamartoma of the genitalia? J Cutan Pathol 2005;32:184-7.  Back to cited text no. 1
Bogetti P, Rolle L, Baglioni EA, Parisi A, Spaziante L, Ruka E, et al. Reconstruction approach to a rare case of acquired scrotal giant muscular hamartoma. Plast Reconstr Surg Glob Open 2016;4:e857.  Back to cited text no. 2
Chen CY, Wang CH, Chiu WK, Chen SG. A huge acquired smooth muscle hamartoma of the scrotum. Indian J Surg 2015;77:111-3.  Back to cited text no. 3
Quinn TR, Young RH. Smooth-muscle hamartoma of the tunica dartos of the scrotum: Report of a case. J Cutan Pathol 1997;24:322-6.  Back to cited text no. 4
Bilgiç Ö, Tunçez Akyürek F, Altınyazar HC. Pseudo darier sign: A Distinctive finding for congenital smooth muscle hamartoma. J Pediatr 2016;169:318.  Back to cited text no. 5
Haydeh G, Massoud A, Pedram N. Multiple smooth muscle hamartoma: Case report and review of the literature. Indian J Dermatol 2009;54:68-71.  Back to cited text no. 6
[PUBMED]  [Full text]  
Hsiao GH, Chen JS. Acquired genital smooth-muscle hamartoma. A case report. Am J Dermatopathol 1995;17:67-70.  Back to cited text no. 7
Semerci B, Ilbey O, Yurtseven O. Acquired penoscrotal smooth muscle hamartoma. J Urol 1997;158:885-6.  Back to cited text no. 8


  [Figure 1], [Figure 2]


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