Sporotrichoid Lymphocutaneous Spread of Metastatic Cutaneous Squamous Cell Carcinoma

Background: Sporotrichoid lymphocutaneous spread is a dermatologic pattern characterized by superficial cutaneous lesions that follow subcutaneous lymphatics. Typically, this is observed when an infection starts at a site of distal inoculation and leads to the development of ascending nodules. The most common causes are fungal and mycobacterial infections. Metastatic cutaneous squamous cell carcinoma (CSCC) typically presents with regional lymphadenopathy. Primary lesions of the external ear and lip have the highest risk of metastasis, followed by the temple, scalp, hands, and feet. Risk factors for metastasis of CSCC include immunosuppression, tumor recurrence, tumor thickness [greater than] 4mm, and perineural or vascular invasion. However, metastasis of CSCC is rarely seen to follow a sporotrichoid lymphocutaneous morphology. Case Information: A 64-year-old female with a past medical history of severe COPD requiring repeated courses of prednisone and continuous oxygen, presented for a rapid growing lesion on her left hand after trauma in the shower at a nursing home. Due to her poor medical condition, she declined recommended biopsy with follow-up surgery. Patient underwent electrodessication and curettage surgery (EDC) followed by imiqumod treatment as she desired the least aggressive treatment. She also complained of a growth on her forearm at the initial visit. She reported after starting imiquimod, the lesion on her left hand has bled, drained and deepened in appearance. She also reported that the previous growth on her left forearm has grown in size and new lesions appeared on her upper arm and armpit. On exam, she had no healing at EDC site. She had developed an ulcer that exceeded the size of the original EDC. She had multiple erythematous, tender nodules of varying sizes on her left arm in a sporotrichoid lymphocutaneous pattern. She had left axillary lymphadenopathy. A biopsy performed of one of the nodules showed CSCC with intravascular and perineural invasion. Tissue cultures were negative for acid-fast bacilli, aerobic bacteria, mycobacteria and fungus. Chest X-ray did not show evidence of metastatic CSCC. Conclusion: This case highlights a rare presentation of sporotrichoid lymphocutaneous spread secondary to CSCC. The differential diagnosis included infectious causes and metastatic CSCC. Surgical excision is the treatment of choice for high-risk CSCC. She presented with signs of metastasis at initial presentation but these were not recognized. At follow up, she rapidly developed signs of metastasis in an unusual pattern. As malignancy is a rare cause of sporotrichoid lymphocutaneous spread, it is important to raise awareness to physicians who may see sporotrichoid pattern to consider the possibility of malignancy in their differential diagnosis, especially when there is a history of malignancy or there is a concomitant visible mass present.