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\begin{document}

\title{A Case of Multiple Acquired Depressed Smooth Muscle Hamartoma}



\author[1]{Kaoru Chiba}%
\author[1]{Itaru Dekio}%
\author[1]{Isami Uno}%
\author[1]{Yoshimasa Nobeyama}%
\author[1]{Akihiko  Asahina}%
\affil[1]{The Jikei University School of Medicine}%


\vspace{-1em}



  
  \date{May 24, 2024}


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\textbf{A Case of Multiple Acquired Depressed Smooth Muscle Hamartoma}

Short title: Multiple Acquired Depressed Smooth Muscle Hamartoma

Kaoru Chiba, MD\textsuperscript{1}, Itaru Dekio, MD\textsuperscript{1},
Isami Uno, MD\textsuperscript{1}, Yoshimasa Nobeyama,
MD\textsuperscript{1}, Akihiko Asahina, MD\textsuperscript{1}

1. Department of Dermatology, The Jikei University School of Medicine,
Tokyo, Japan

Corresponding Author: Yoshimasa Nobeyama

Department of Dermatology, The Jikei University School of Medicine

3-25-8, Nishi-Shimbashi, Minato-ku, Tokyo, 105-8461, Japan

Tel: +81-3-3433-1111 Ext. 3341; Fax: +81-3-5401-0125

E-mail \emph{nobederm@jikei.ac.jp}

The authors received no financial support for this study.

The authors have no conflicts of interest to declare.

988 words, 2 figures

\textbf{Key words} : hamartoma, smooth muscle, multiple, acquired,
depressed

\textbf{Key Clinical Message}

This case report presents a 40-year-old male with multiple acquired
depressed smooth muscle hamartoma. The report for the first time
describes smooth muscle hamartoma characterized by multiple
distribution, acquired onset, and depressed appearance.

\textbf{Introduction}

Smooth muscle hamartoma (SMH) is a benign skin tumor characterized by
the proliferation of smooth muscle bundles, primarily originating from
the pilomotor muscles. SMH most commonly presents in the lumbar and
sacral regions and typically manifests within the first six months of
life. The clinical presentation of SMH is characterized by pale brown
macules with slightly indistinct borders. To date, there have been few
reported cases of multiple SMH in the literature \textsuperscript{1}.
Additionally, there are very limited reports of acquired
SMH\textsuperscript{2}. In this report, we present a unique case of
acquired SMH with multiple distribution and depressed appearance.

\textbf{Case Report}

A 40-year-old French male patient was referred to us with a 7-year
history of multiple pigmented macules on the trunk and extremities. The
patient had no history of diabetes mellitus or injections, including
steroids and insulin. No relevant clinical manifestations were observed
among his family members. Physical examination revealed multiple,
slightly depressed, and pigmented macules ranging from 1 to 3 cm in
diameter without hypertrichosis on the trunk and extremities
(\textbf{Figure 1} ).

Histopathological examination demonstrated irregularly distributed,
bundled pale eosinophilic structures of various sizes with oval-shaped
nuclei in the upper dermis by hematoxylin and eosin staining
(\textbf{Figure 2a} ). There was no discernible increase in the number
of melanocytes in the epidermis or hair follicles. Masson trichrome
staining showed that the irregularly distributed and variously sized
bundled structures were less stained than collagen fibers in the dermis
(\textbf{Figure 2b} ). These findings collectively indicated an aberrant
proliferation of mature smooth muscle in the upper dermis. Based on
these findings, the diagnosis of SMH was made. The patient was followed
for 6 months, during which time there was no change in the cutaneous
manifestations.

\textbf{Discussion}

This case presents a distinct clinical manifestation of SMH in three
notable aspects: its multiple occurrences, its acquired nature, and its
depressed appearance. Initially, a unique appearance of multiple
occurrences in the case should be reviewed. Because of several case
reports with multiple Becker's nevi \textsuperscript{3,4} , in the
current case, Becker's nevi were considered as a potential differential
diagnosis. However, due to the absence of hypertrichosis and the lack of
epidermal changes, the present case is reasonably diagnosed as
SMH\textsuperscript{5}. Based on our current understanding, there have
been a few case reports of multiple SMH in localized areas of the body,
such as the head and scrotum \textsuperscript{6,7} . Nevertheless, no
instances of widespread multiple SMH throughout the body have been
documented in the English literature. Considering it, our case is deemed
to be exceedingly rare.

While a higher incidence of single lesions in congenital instances has
been suggested \textsuperscript{1}, a definitive clinical presentation
of acquired cases has not been fully established, primarily due to the
limited number of case reports regarding acquired instances. The
scarcity of clinical photographs in the literature might lead to the
difficulty in identifying cases with similar clinical presentations to
this case. Although there is a report of multiple SMH arising in a
single family \textsuperscript{8,9} , this case had no evidence of
familial occurrence.

The onset of this case at 36 years of age is particularly noteworthy. In
general, SMH is considered congenital, and acquired cases are relatively
rare. According to a case report published in 2021 \textsuperscript{2},
there had been only 25 cases of acquired SMH reported internationally.
Among these, 14 cases occurred after the age of 30. In light of these
findings, it is conceivable that the presented case is not uncommon as
an acquired instance of SMH.

Lastly, a distinctly depressed appearance exhibited in the present case
should be described. The case should be clinically distinguished from
anetoderma, atrophoderma of Pasini and Pierini, scleroderma en plaques,
lupus profundus, and discoid lupus erythematosus. In our case, we did
not observe the disappearance or fragmentation of elastic fibers as is
typically seen in anetoderma \textsuperscript{10}. Additionally, there
was a remarkable proliferation of smooth muscle, which is not usually
seen in atrophoderma of Pasini and Pierini \textsuperscript{11,12} .
Furthermore, lilac rings indicative of scleroderma en plaques,
subcutaneous indurations associated with lupus profundus, or erythema
with hyper- or hypo-keratosis suggestive of discoid lupus erythematosus
were all absent. These considerations reinforce the diagnosis of SMH in
this case. As per our current understanding, there exists only a
solitary report documenting SMH with a depressed
appearance\textsuperscript{13}, making our case exceptionally uncommon.

In conclusion, we have encountered a case of SMH with distinctive
features. We consider this case to be clinically rare for three reasons:
its multiple occurrences, its acquired nature, and its depressed
appearance. It is necessary for dermatologists to consider SMH as one of
the differential diagnoses when patients show multiple depressed
macules.

\textbf{Acknowledgment:} None

\textbf{Statement of Ethics:} The study protocol was approved by The
Ethics Committee of The Jikei University School of Medicine and the
patient provided written informed consent.

\textbf{Consent statement:} Written informed consent was obtained from
the patient to publish this report in accordance with the journal's
patient consent policy.

\textbf{Data Availability Statement:} Additional data sharing is not
applicable to this article due to ethical restrictions.

\textbf{Author Contributions}

Kaoru Chiba: The author contributed to data curation, resources, and
drafting the original paper.

Itaru Dekio: The author contributed to resources and preparation for
paper writing.

Isami Uno: The author contributed to resources.

Yoshimasa Nobeyama: The author contributed to conceptualization and
project administration.

Akihiko Asahina: The author contributed to review and supervision.



\textbf{References}

1 Haydeh G, Massoud A, Pedram N. Multiple smooth muscle hamartoma: case
report and review of the literature. \emph{Indian J Dermatol}
2009.\textbf{54} : 68-71.

2 Marin-Hernandez E, Ramirez-Rico A. Acquired smooth muscle hamartoma
with sebaceous component. \emph{Bol Med Hosp Infant Mex}
2022.\textbf{79} : 326-333.

3 Leszczynska M, Pisano C, Haller CN, Diaz LZ. A case of multiple,
bilateral Becker's Nevi of the trunk and lower extremities in a young
girl: A case report. \emph{SAGE Open Med Case Rep} 2022. \textbf{10} :
2050313X221131862.

4 Ramot Y, Maly A, Zlotogorski A. A rare case of multiple Becker's nevi
in a checkerboard mosaic pattern. \emph{J Eur Acad Dermatol
Venereol}2014. \textbf{28} : 1573-1574.

5 Schrom KP, Shah SD, Rohr BR. Clinicopathologic discordance: Congenital
smooth muscle hamartoma clinically mimics reticulated vascular
lesion.\emph{JAAD Case Rep} 2022. \textbf{26} : 9-12.

6 Jain S, Patro S, Darkase B \emph{et al.} Multiple acquired smooth
muscle hamartomas with thick-walled blood vessels on scalp. \emph{J
Cutan Pathol} 2018. \textbf{45} : 629-632.

7 Hsiao GH, Chen JS. Acquired genital smooth-muscle hamartoma. A case
report. \emph{Am J Dermatopathol} 1995. \textbf{17} : 67-70.

8 Gualandri L, Cambiaghi S, Ermacora E \emph{et al.} Multiple familial
smooth muscle hamartomas. \emph{Pediatr Dermatol} 2001. \textbf{18} :
17-20.

9 Garcia-Gavin J, Perez-Perez L, Allegue F \emph{et al.} Multiple
congenital familial smooth muscle hamartoma in two
siblings.\emph{Dermatol Online J} 2012. \textbf{18} : 7.

10 de Faria Melo M, de Faria Melo I, Escobar GF. Secondary
Anetoderma.\emph{JAMA Dermatol} 2021.

11 Handler MZ, Alshaiji JM, Shiman MI \emph{et al.} Congenital
idiopathic atrophoderma of Pasini and Pierini. \emph{Dermatol Online
J}2012. \textbf{18} : 4.

12 Eichhoff G. Atrophoderma of Pasini and Pierini in a patient with
concomitant psoriasis: Response to methotrexate. \emph{JAAD Case
Rep}2019. \textbf{5} : 277-279.

13 Tirado-Sanchez A, Santamaria-Roman A, Ponce-Olivera RM. Smooth muscle
hamartoma presenting as a morphea-like plaque. \emph{Indian J Dermatol
Venereol Leprol} 2010. \textbf{76} : 290-291.

\textbf{Figure legends}

\textbf{Figure 1. Clinical manifestation}

Multiple depressed and pigmented macules, ranging in diameter from 1 to
3 cm, are observed on the back.

\textbf{Figure 2. Histopathological findings}

a) Irregularly distributed and variously sized bundled pale eosinophilic
structures with oval-shaped nuclei are present in the upper dermis
(hematoxylin and eosin stain, \selectlanguage{ngerman}×100). b) Irregularly distributed and
variously sized bundled structures were less stained than collagen
fibers in the dermis by Masson trichrome stain (×100).\selectlanguage{english}
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