Scalp rhinosporidiosis: Recognising tumour-like presentations

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A 36-year-old man from Eastern India, who works as a farmer, reported a 9-month history of painless, asymptomatic swelling on his scalp that covered his left parietal region. Upon cutaneous examination, there was a single skin-coloured to erythematous growth that resembled a tumour, measuring 2 × 1.5 cm and showing no surface changes. It felt firm to the touch, non-tender, and adhered to the skin [Figures 1]. Other than an unrecorded nasal surgery performed around three years ago, the patient had no prior history of trauma, surgery, or comparable lesions. He has no other comorbidities, such as diabetes, tuberculosis, deep fungal infection, etc., and was not on any immunosuppressives. HIV, HbsAg, and HCV viral markers were all negative. The haemogram and biochemical results were within normal limits. We took into consideration differentials of benign tumours such as trichilemmal cyst, epidermoid cyst, fibroma, and cyst. For further evaluation, an excisional biopsy of the sample was done, and the sample was sent for histopathological examination [Figures 2a and b]. Haematoxylin and eosin stain revealed mature and immature sporangiospores and numerous endospores against an inflammatory background. No tumour or polyp was found by rhinoscopy. Ocular and nasopharyngeal examinations were normal. The results of other systemic examinations were also normal. Hence, based on the histopathological findings, a diagnosis of cutaneous rhinosporidiosis was considered, and treatment was started with dapsone (100 mg) once a day for 6 months. After three weeks following excision, the lesion began to heal, and two months later, full clearance was observed. The patient did not have recurrence of the lesion and is currently doing well without any recurrence.

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Figure 1:

Single skin-coloured to erythematous tumour-like growth of size 2 × 1.5 cm (Blue arrow) present over the left parietal area.

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Figure 2a:

Sporangium (black arrow) with endospores (Haematoxylin and eosin, 100x).

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Figure 2b:

Sporangium (black arrow), endospores (black star), and stratified squamous epithelium (red arrow) (Haematoxylin and eosin, 40x).

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Rhinosporidiosis is a chronic granulomatous disease of infective aetiology. Rhinosporidium seeberi was once assumed to be the cause, but Microcystis aeruginosa, a cyanobacterium, has lately been suggested as the cause. India and Sri Lanka are endemic for the disease, but it has also been reported in Iran, South America, and the United States.¹ According to reports, West Bengal, Odisha, Chhattisgarh, and Tamil Nadu are the regions in India, where the disease is most common.^1,2 Males are more likely than females to be affected. One of the main risk factors in endemic areas has been identified as bathing in bodies of water, such as lakes with stagnant water.¹ It most frequently affects the nasal mucosa, nasopharynx, and soft palate, and less frequently affects the maxillary sinus, conjunctiva, and lacrimal sac.² It manifests clinically as a red, polypoidal mucosal lesion. It can spread through direct skin inoculation, haematogenous dissemination, lymphatic dissemination, and autoinoculation. Three different kinds of cutaneous lesions have been identified: primary cutaneous lesions, which are extremely uncommon, disseminated lesions with visceral involvement, and nodules surrounding nasal polyps.³ Additionally, lesions that resemble pyogenic granulomas, furuncles, ecthyma, lipomas, soft tissue tumours, tuberculosis verrucosa cutis, viral warts, donovanosis, subcutaneous nodules, cutaneous horn, subcutaneous giant masses, and keratoacanthoma-like crateriform lesions have been described.^4,5 Further, all variations had been reported in one case.² Aspiration cytology makes the diagnosis simple; however, in the present case, rhinosporidiosis was not suspected at presentation. The gold standard for diagnosis is histopathology. Dapsone is the preferred medication. The preferred course of treatment is surgical excision. Although our thorough examination for involvement of other cutaneous sites and systems did not reveal any additional lesions. The development of a cutaneous lesion may be an early indication of dissemination. This case is documented for a solitary lesion, an unusual place of presentation, and isolated cutaneous presentation.