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Year : 2017  |  Volume : 8  |  Issue : 6  |  Page : 505-507  

Acquired smooth muscle hamartoma of foot: A rare entity

Department of Dermatology, D. Y. Patil Medical College and Hospital, Navi Mumbai, Maharashtra, India

Date of Web Publication14-Nov-2017

Correspondence Address:
Chirag Desai
Department of Dermatology, D. Y. Patil Medical College and Hospital, Nerul, Navi Mumbai, Maharashtra
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/idoj.IDOJ_392_16

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How to cite this article:
Desai C, Sheth P, Patil S. Acquired smooth muscle hamartoma of foot: A rare entity. Indian Dermatol Online J 2017;8:505-7

How to cite this URL:
Desai C, Sheth P, Patil S. Acquired smooth muscle hamartoma of foot: A rare entity. Indian Dermatol Online J [serial online] 2017 [cited 2020 May 28];8:505-7. Available from: http://www.idoj.in/text.asp?2017/8/6/505/218340


Smooth muscle hamartomas (SMH) are benign proliferation of smooth muscle bundles within dermis. They may arise from arrector pilorum, dartos, vulval, mammillary, or vessel wall.[1] They are of two types; congenital smooth muscle hamartoma usually manifests at birth and presents over the trunk or extremities, whereas the acquired variant is comparatively rare and arises later in life.[1]

A 28-year-old female presented with an asymptomatic lesion over the medial aspect of the right heel since 8 to 9 months. There was no history of similar lesions elsewhere on the body, and family history of such lesions was negative. On enquiry, patient denied taking any treatment for it in the past, and there was no loss of sensation over the lesion. On examination, the lesion was a flat-topped erythematous plaque located on the medial side of right heel [Figure 1]. There was no tenderness. Touch, pain, and temperature sensations over the plaque were well preserved. A presumptive diagnosis of collagenoma and bursitis was considered. A biopsy was done which revealed epidermal hyperplasia with orthokeratotic hyperkeratosis of statum corneum. Lower dermis demonstrated bundles of smooth muscles placed above the subcutaneous fat [Figure 2] and [Figure 3]. Hence, a final diagnosis of acquired SMH was made. The patient was advised surgical excision of the lesion.
Figure 1: Single erythematous flat-topped elevated plaque over the medial aspect of the rightheel

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Figure 2: Multiple smooth muscle bundles placed in mid and deep dermis near the deep dermal vessels (H and E, ×100)

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Figure 3: Smooth muscle bundles in deep dermis (H and E, ×400)

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SMH arises from the smooth muscle cells located in arrector pili muscle, dartos muscle, vascular smooth muscle, muscularis mammillae, and areola. Congenital SMH is a more common entity comparatively and usually arises at birth.[1] It appears as variably-sized papules, plaques, or patches, and the usual location is either the trunk or extremities. Pseudo-Darier's sign is positive which comprises transient piloerection and elevation or induration of lesional skin. Darier's sign refers to urtication with erythematous halo in response to stroking of lesion in a case of mastocytosis.[1]

Acquired smooth hamartoma is a rare entity, usually located on the skin of the forearm, chest, neck, scrotum, penis, labia majora, or shoulder. Most of the cases in literature were reported to have originated from arrector pilorum and dartos muscle. Pseudo-Darier's sign is negative in this variant.[1]

Clinically, the lesion of acquired SMH is associated with hyperpigmentation and hypertricosis, with becker's nevus being the closest differential. However, there is a report in literature wherein only an asymptomatic and indurated plaque was present on the anterior aspect of neck for 10 years.[2] Another report mentions the occurrence of a tender skin-colored nodule on the sole of a right foot in a 21-year-old female without hyperpigmentation or hypertichosis.[3]

Biopsy demonstrates smooth muscle bundles with each cell having cigar-shaped nucleus, being haphazardly arranged throughout the dermis, especially around the vessels. In most of the cases mentioned in the literature, these muscle cells in the dermis arise from either dartos muscle or arrector pilorum muscle; however, in our case, the plaque was present on the sole where both these muscle groups are absent. Therefore, most probably, the muscle bundles in dermis in our case appear to have been caused by the proliferation of smooth muscles from the vessels in deep dermis. There is a report of a similar case of acquired SMH arising from the inner aspect of the sole.[3] Surgical excision is curative in this condition.

To the best of our knowledge, there are very few reports of acquired SMH in world literature [Table 1]. We report this case because of the unusual presentation of this rare entity both in regard to morphology and site.
Table 1: Available case reports of acquired smooth muscle hamartoma in English literature

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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.


Dr. Bhavna Doshi, Assistant Professor, Dermatology Department at BJMC, Pune, India.[5]

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Conflicts of interest

There are no conflicts of interest.

   References Top

Adulkar SA, Dongre AM, Thatte SS, Khopkar US. Acquired smooth muscle hamartoma. Indian J Dermatol Venereol Leprol 2014;80:483.  Back to cited text no. 1
[PUBMED]  [Full text]  
Darling TN, Kamino H, Murray JC. Acquired cutaneous smooth muscle hamartoma. J Am Acad Dermatol 1993;28:844-5.  Back to cited text no. 2
Lee D, Kim SH, Hong SK, Sung HS, Hwang SW. A case of acquired smooth muscle hamartoma on sole. Ann Dermatol 2009;21:78-80.  Back to cited text no. 3
Bari A, Rahman S. Acquired smooth muscle hamartoma. Indian J Dermatol Venereol Leprol 2006;72:178  Back to cited text no. 4
Yancovitz M, Gonzalez ME, Votava HJ, Walters R, Kundu R, Shupack JL. Acquired smooth muscle hamartoma. Dermatol Online J 2009;15:12.  Back to cited text no. 5


  [Figure 1], [Figure 2], [Figure 3]

  [Table 1]


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