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Table of Contents 
Year : 2022  |  Volume : 67  |  Issue : 5  |  Page : 629
Appearances can be deceptive: An intriguing case of a keloidal mass

1 Department of Dermatology, IMS and SUM Hospital, Bhubaneswar, Odisha, India
2 Department of Pathology, IMS and SUM Hospital, Bhubaneswar, Odisha, India

Date of Web Publication29-Dec-2022

Correspondence Address:
Akash Agarwal
Department of Dermatology, IMS and SUM Hospital, Bhubaneswar, Odisha
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijd.ijd_783_21

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How to cite this article:
Behera D, Debata I, Mohapatra D, Agarwal A. Appearances can be deceptive: An intriguing case of a keloidal mass. Indian J Dermatol 2022;67:629

How to cite this URL:
Behera D, Debata I, Mohapatra D, Agarwal A. Appearances can be deceptive: An intriguing case of a keloidal mass. Indian J Dermatol [serial online] 2022 [cited 2023 Feb 5];67:629. Available from:

   Case History, Examination, and Investigation Findings Top

A 57-year-old female presented to the dermatology outpatient department with an asymptomatic brownish growth over the left upper back of 1-year duration [Figure 1]. Treatment history comprised multiple sessions of intralesional corticosteroids and cryotherapy with a working diagnosis of keloid, with minimal improvement. On cutaneous examination, there was a single ill-defined indurated fleshy nodule with prominent telangiectasia and underlying background hyperpigmentation. Laboratory works up were within normal limits. An excisional biopsy was planned, and histopathological analysis revealed a partially circumscribed tumor in the papillary dermis encroaching the epidermis [Figure 2]a. It was comprised of spindle cells arranged in short and long intersecting fascicles, bundles, and in a storiform pattern [Figure 2]b. The cells had elongated cigar-shaped to pleomorphic hyperchromatic nuclei with perinuclear vacuolation, conspicuous nucleoli, and moderate to abundant amounts of eosinophilic cytoplasm (Mitosis = 1–2/hpf). Few bizarre tumor giant cells were also present [Figure 2]c. Immunohistochemistry analysis was carried out which revealed vimentin and smooth muscle actin (SMA) positivity with CD34 and CD68 being negative [Figure 2]d and [Figure 2]e.
Figure 1: Single ill-defined indurated fleshy nodule with prominent telangiectasia and underlying background hyperpigmentation over the left upper back

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Figure 2: (a) (H and E, 40×) showing thinned out keratinized stratified squamous epithelium with papillary dermis showing a tumor comprised of spindle cells. (b) (H and E, 100×) showing the tumor cells arranged in intersecting fascicles. (c) (H and E, 400×) showing intersecting fascicles of spindle cells, having abundant eosinophilic cytoplasm, cigar shaped nucleus, moderate nuclear atypia and increased mitotic figure including atypical forms (arrowed). (d) (IHC- Vimentin, 100×) showing strong cytoplasmic positivity. (e) (IHC- SMA, 400×) showing strong cytoplasmic positivity

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What is your diagnosis?


Dermal leiomyosarcoma.

   Discussion Top

Leiomyosarcoma (LMS) of the skin is a very rare neoplasm comprising 2–3% of all skin sarcomas and 0.04% of all neoplasms overall.[1] The tumor can arise either from arrector pili muscle (dermal leiomyosarcoma) or from the vascular smooth muscle of subcutaneous adipose tissue (subcutaneous leiomyosarcoma). The dermal type usually presents in the fifth to seventh decade, having an indolent course and depicting a male preponderance (3:1). The most common predisposing factors reported are trauma and radiation. Clinically, the lesions are usually single indurated nodules, 1–3 cm in size. They can be painful, pruritic, or asymptomatic with rare surface ulceration. They occur most commonly on the extremities, the thigh being the commonest. Local recurrence rates are high (up to 35%). These tumors very rarely metastasize (3–14%).[2]

The clinical picture in our patient mimicked that of a keloid but the indurated fleshy appearance of the nodule with surface telangiectasia raised suspicion of an underlying malignancy. Differential diagnoses considered initially were dermatofibroma, dermatofibrosarcoma protuberans (DFSP), lobomycosis and keloidal basal cell carcinoma (Keloidal BCC). Histopathological analysis however revealed that we were dealing with a spindle cell malignant neoplasm of the skin which further revised our differential diagnosis to include malignant peripheral nerve sheath tumor, leiomyosarcoma, desmoplastic malignant melanoma (DMM), and cutaneous spindle cell squamous cell carcinoma (SCSCC). Immunohistochemistry, therefore, became instrumental in coming to a definitive diagnosis.

Keloidal BCC is a clinical type of BCC that clinically mimics a keloid (as in our case) and has keloidal collagen between the basaloid cells on histopathology. The absence of any features of BCC on histopathology however ruled out this possibility. Dermatofibroma (benign fibrous histiocytoma) presents as a firm to hard hyperpigmented plaque or nodule having ill-defined intersecting bundles of spindle cells with collagen trapping on histopathology.[3] DFSP, on the other hand, is a locally aggressive low-grade spindle-shaped neoplasm that presents as a pink to purple plaque with surrounding telangiectasia having similar histology as that of dermal LMS. Immunohistochemistry helps differentiate between these entities with dermatofibroma and DFSP showing CD34 positivity which was absent in our case. The incidence of malignant peripheral nerve sheath tumor (MPNST) in the general population is 0.001% and it usually occurs in patients of neurofibromatosis type 1 with a sudden change in the size of neurofibroma, pain, or new-onset neurological deficit. Histopathology is similar to LMS but on IHC, S100 positivity goes in favor of MPNST. Another histopathological differential considered was DMM which typically occurs in male patients on chronically sun-exposed areas, presenting as a firm papule, nodule, or plaque. S100 positivity on IHC points toward DMM which was absent in our case. Cutaneous SCSCC also histologically mimics dermal LMS due to poor differentiation and minimal signs of keratinization. P63 positivity on IHC and derivation of tumor from an epidermal focus of atypical keratinocytes points in favor of SCSCC.[3]

Upon confirmation of diagnosis, the patient underwent wide local excision with a 1 cm tumor-free margin. Overall, the prognosis of dermal LMS is excellent but these tumors do tend to recur. The patient must be followed up regularly to rule out such a possibility.

Our patient was treated as a keloid for over a year with minimal response prompting us to think about different underlying pathology. Reports of delayed diagnosis of dermal LMS presenting as a keloid have been scarcely reported in the literature.[4],[5] It should be borne in mind that a delay in diagnosis of dermal LMS can be detrimental for the patient considering the rare possibility of metastasis (3–14%). Thus, a lower threshold for biopsy in patients with long-standing keloids not responsive to conventional therapy should be kept.

   Learning Points Top

Primary leiomyosarcoma of skin (LMS) is a rare tumor, accounting for only 2%–3% of all soft tissue sarcomas.

Histopathologically, it is characterized by tumor composed of spindle cells arranged in short and long intersecting fascicles, bundles, and in a storiform pattern with cells having elongated cigar-shaped to pleomorphic hyperchromatic nuclei.

Immunohistochemistry shows positivity for vimentin and smooth muscle actin.

Differential diagnosis of keloidal mass is keloidal basal cell carcinoma, dermatofibrosarcoma protuberans, lobomycosis, and leiomyosarcoma.

A lower threshold for biopsy in patients with long standing keloids nonresponsive to conventional therapy, should be considered.

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.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

   References Top

Rouhani P, Fletcher CD, Devesa SS, Toro JR. Cutaneous soft tissue sarcoma incidence patterns in the U.S.: An analysis of 12,114 cases. Cancer 2008;113:616-27.  Back to cited text no. 1
Winchester DS, Hocker TL, Brewer JD, Baum CL, Hochwalt PC, Arpey CJ, et al. Leiomyosarcoma of the skin: Clinical, histopathologic, and prognostic factors that influence outcomes. J Am Acad Dermatol 2014;71:919-25.  Back to cited text no. 2
Elbendary A, Griffin JR, Elston DM, Verma SB. Cellular dermatofibroma: A hyperkeratotic indurated plaque on the thigh. Indian Dermatol Online J 2016;7:308-10.  Back to cited text no. 3
[PUBMED]  [Full text]  
Sleiwah A, Clinton A, Herbert K. Delayed diagnosis of dermal leiomyosarcoma mimicking keloid scar. BMJ Case Rep 2018;2018:bcr2017222616.  Back to cited text no. 4
Nicholas RS, Stodell M. An important case of misdiagnosis: Keloid scar or high-grade soft-tissue sarcoma? BMJ Case Rep 2014;2014:bcr2014203600.  Back to cited text no. 5


  [Figure 1], [Figure 2]


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