Cutaneous leiomyoma or piloleiomyoma, are benign smooth muscle tumor arising from the arrector pili muscles of the skin, vascular smooth muscle, or dartos muscle . It is a relatively uncommon neoplasm, accounting for a small fraction of all benign soft tissue tumors. (1)

These lesions typically present as firm, skin-colored to reddish-brown nodules in the dermis or subcutaneous tissue, most commonly involving the extremities, trunk, or genital region.

They may be solitary or multiple, with multiple lesions often associated with hereditary leiomyomatosis and renal cell carcinoma (HLRCC) syndrome, linked to fumarate hydratase (FH) gene mutations (2)

Although benign, these lesions are important to recognize due to their potential association with genetic syndromes, their painful nature, and the need for differentiation from other spindle cell tumors

CASE PRESENTATION

A 46-year-old woman  presented to the surgery outpatient with multiple cuatneous  lumps on the shoulder, right and left arm . These  were present for the last 2-3 years and were slowly growing in size . On examination they measured between 2-3 cm were firm , mobile and non tender  . The patient did not give any history of uterine fibroids .

Complete blood counts, urea, creatinine, electrolytes, liver function tests were all normal and an excision biopsy was performed for all three lumps with a clinical diagnosis of Lipoma given the multiple nature of the lesions and there location

Histopathological Findings

Biopsies from all three lesions displayed comparable features. The sections showed skin with intact epidermis, dermis, and subcutaneous tissue. The dermis contained a well-defined nodular proliferation of smooth muscle cells arranged in interlacing fascicles. The tumor cells possessed elongated, blunt-ended (“cigar-shaped”) nuclei, fine chromatin, and eosinophilic cytoplasm with indistinct cell borders. No cytologic atypia, necrosis, or significant mitotic activity was identified. (Fig 1 )

Immunohistochemistry was positive for smooth muscle active (SMA)  and Desmin and negative for S100  ( Fig 2 )Given the patient's clinical presentation and her histopathological findings and immunohistochemistry markers , a diagnosis of multiple cutaneous leiomyomas was made .

Fig 1  H &E  shows demal nodule of spindle cells  (10 X)

FIG  2    Diffuse positivity for SMA   and Desmin  on IHC (40x)

Differential Diagnosis

Clinically, cutaneous leiomyoma may mimic several other painful dermal or subcutaneous nodules. The important   ones being dermatofibroma , Neurofibroma or lipoma .

In the present case diagnosis was based on hitopathology findings  and immunohistochemistry markers  .

Treatment

The treatment of cutaneous leiomyomas is dictated by the number of lesions and the degree of discomfort or cosmetic nuisance. When only a few lesions are present, surgical excision is the gold standard for complete removal  .

Outcome and follow up

The patient reported significant symptomatic relief following surgical excision of the lesions. Considering the presence of multiple cutaneous leiomyomas, evaluation for Hereditary Leiomyomatosis and Renal Cell Carcinoma (HLRCC) syndrome was advised. Genetic counselling and FH gene testing were recommended. Renal imaging performed during follow-up revealed no evidence of renal tumors, and there was no clinical or imaging correlation with uterine leiomyomas. The patient continues to remain under periodic surveillance  one year after treatment

DISCUSSION   

Reed’s syndrome, also known as multiple cutaneous and uterine leiomyomatosis (MCUL), is a rare genetic disorder characterized by the presence of multiple smooth muscle tumors primarily involving the skin and uterus. The condition results from mutations in the fumarate hydratase (FH) gene, which encodes an enzyme critical to the citric acid (Krebs) cycle.  (3)

In the present case, the patient developed multiple cutaneous leiomyomas over the shoulder and hand, which had gradually increased in size and number over several years. Histopathological examination and immunohistochemistry confirmed the diagnosis of smooth muscle tumors. However, no associated uterine or renal lesions were detected on imaging studies. Genetic counselling and FH gene testing were advised, and the patient remains under regular clinical and imaging surveillance

The treatment of cutaneous leiomyomas is dictated by the number of lesions and the degree of discomfort or cosmetic nuisance. When only a few lesions are present, surgical excision is the gold standard for complete removal  (4)

Learning Points

• Cutaneous leiomyomas, though rare, are important to recognize due to their potential clinical significance.
• The presence of multiple lesions should prompt evaluation for Hereditary Leiomyomatosis and Renal Cell Carcinoma (HLRCC) syndrome.
• Genetic counselling and FH gene testing play a crucial role in identifying syndromic associations.
• Regular surveillance is essential to detect possible systemic malignancies, particularly renal tumors.
• Histopathological confirmation remains the gold standard for accurate diagnosis and for distinguishing leiomyomas from other cutaneous neoplasms.

REFERENCES

1. Alam NA, Barclay E, Rowan AJ, Tyrer JP, Calonje E, Manek S, et al. Clinical features of multiple cutaneous and uterine leiomyomatosis: an underdiagnosed tumor syndrome. Arch Dermatol 2005 Feb;141(2):199-206
2. Toro JR, Nickerson ML, Wei MH, Warren MB, Glenn GM, Turner ML, et al. Mutations in the fumarate hydratase gene cause hereditary leiomyomatosis and renal cell cancer in families in North America. Am J Hum Genet 2003 Jul;73(1):95-106.
3. Valcarcel-Jimenez L, Frezza C. Fumarate hydratase (FH) and cancer: a paradigm of oncometabolism. Br J Cancer 2023 Nov;129(10):1546-1557.
4. Holst VA, Junkins-Hopkins JM, Elenitsas R. Cutaneous smooth muscle neoplasms: clinical features, histologic findings, and treatment options. J Am Acad Dermatol 2002 Apr;46(4):477-490, quiz, 491-494