Introduction

Sporotrichosis is a subacute or chronic infectious disease caused by the dimorphic fungi that fall within the Sporothrix schenckii complex.[1] Recognized globally, this mycosis is especially common in tropical and subtropical regions and stands as the most frequent subcutaneous mycosis in Latin America.[2] The infection traditionally occurs through the traumatic inoculation of the pathogen into the skin, usually via contact with contaminated environmental sources such as soil, wood, or plant material.[3] Clinically, the disease is primarily categorized into localized forms, such as lymphocutaneous sporotrichosis and fixed sporotrichosis.[1,4]

In contrast, disseminated sporotrichosis is a rare, severe manifestation characterized by multiple lesions affecting two or more non-contiguous anatomical sites, without visceral involvement.[4] Systemic forms, involving multiple visceral organs or the central nervous system, are also possible. Disseminated disease occurs most frequently in patients with underlying immune compromise, including those with conditions such as diabetes mellitus, HIV infection, or those undergoing immunosuppressive therapy.[5]

The gold standard for diagnosing sporotrichosis remains the isolation and identification of the Sporothrix species in culture.[6,7] However, obtaining definitive results from culture can take a substantial amount of time, sometimes up to four to six weeks,[6] which may delay the prompt initiation of critical antifungal treatment, especially in severe cases.

Fine Needle Aspiration Cytology (FNAC) serves as a valuable and efficient complementary tool for diagnosis. It is a rapid, minimally invasive, and cost-effective procedure that allows for the early presumptive identification of fungal elements.[7] FNAC smears which reveal yeast-like structures, which may be round, oval or elongated (“cigar-shaped’’) seen within macrophages or scattered extracellularly, along with inflammatory background featuring granulomas or acute suppurative changes.[6] The presence of numerous fungal elements in cytological or histological material is often associated with immunocompromised patients or certain animal infections (e.g., felines), distinguishing them from the scarcity typically observed in immunocompetent human hosts.

Given the rarity of disseminated sporotrichosis and the limited number of reports describing its diagnosis via FNAC, highlighting the utility of this method is important. FNAC, complemented by special stains and microbiological culture, facilitates rapid diagnosis and the timely establishment of appropriate treatment regimens, particularly in atypical clinical presentations such as multiple soft tissue nodules.

Case Report

Case 1:

A 47-year-old male presented to dermatology out patient department with multiple nodules over the skin. The nodules were present over the medial aspect of right foot and shin of the left leg. The nodules were smooth, painless, and had been slowly growing over the past four months. The patient did not have any symptoms of fever, pain or oozing from the nodules. In the past, few months ago a similar nodule had appeared and healed on its own.

The patient had been diagnosed with type 2 Diabetes mellitus a year ago, which raised concern about his immune response and healing capacity.

On local examination, the nodules were located in subcutaneous region, firm, not freely mobile. Size of nodules ranged from 2 x 1 cm to 1 x 1 cm. There was no evidence of tenderness, erythema or ulceration over the skin (There was no evidence of regional or generalized lymphadenopathy or hepatosplenomegaly). Laboratory examination including Complete blood count, Erythrocyte sedimentation rate, C-reactive protein, urine examination were within normal limit. HbA1c- 7.6 % and random blood sugar was 250 mg/dl.

Radiological finding were not available.

Case 2:

A 58-year-old male presented to dermatology out patient department with multiple nodules over the skin.The nodules were present over the tip of middle finger of left hand and on the distal, ventral aspect of right forearm. The nodules were irregular and ulcerated. The patient did not have any symptoms of fever, pain or oozing from the nodules.

The patient had been diagnosed with type 2 Diabetes mellitus five years ago, which raised concern about his immune response and healing capacity.

On local examination, the nodules were located in subcutaneous region, firm, not freely mobile. Size of nodules were 2 x 2 cm. There was no evidence of tenderness or erythema. Nodules showed ulceration over the skin. There was no evidence of regional or generalized lymphadenopathy or hepatosplenomegaly. Laboratory examination including Complete blood count, Erythrocyte sedimentation rate, C-reactive protein, urine examination were within normal limit. HbA1c- 9.2% and Random blood sugar was 420 mg/dl.

Radiological finding were not available.

Typical clinical presentation on extremities of both cases are shown in Fig. 1.

Fig. 1: (A,B) Clinical image showing  smooth, painless nodule over anterior aspect of leg.

Fig. 2: (A, B) FNAC smears showing plenty of neutrophils and multinucleate giant cells.

To investigate further, in both cases, fine needle aspiration cytology was performed. The sample yielded a thick, white, pultaceous material.

Smears were prepared and slides were stained with Hematoxylin and Eosin (H and E ) and May-Grunwald Giemsa stain (MGG) stain. Fig. 2 shows FNAC smears which revealed plenty of neutrophils, multi nucleated giant cells, epithelioid clusters along with plenty of fungal organisms. These fungal organisms were oval to elongated, cigar-shaped yeast forms scattered in the background and nestled within giant cells. These findings pointed at cytomorphological diagnosis of fungal infection morphologically consistent with possibly sporotrichosis. With the diagnosis in hand, antifungal therapy was initiated.

A second pass was done and the material was sent to microbiology department in Sabouraud Dextrose Agar medium. On the seventh day, the culture showed cream‑colored, moist and smooth which converted to brown black color because of melanin synthesis in Fig. 3.

Fig. 3: (A,B) Culture of sample taken from FNAC in Sabouraud dextrose agar medium.(C,D) Sporothrix schenkii: Lactophenol cotton blue mount.

Fig. 4: (A,B) FNAC smears showing cigar shaped fungal organisms extracellularly and within cytoplasm of giant cells-PAS stain. (C,D) Smears showing fungal organisms which are PAS positive (PAS, x10 & x40)

Lactophenol Cotton Blue staining was performed on sub culture which showed delicate branching septate hyphae with slender, short, conidiophores with tapering tips and surrounding pyriform conidia in a flower-like arrangement or as individual thick-walled, dark brown conidia attached directly to the hypha often in dense sleeve-like pattern.

The patients responded well to anti fungal treatment and the nodules resolved without complication.

Discussion

The cases described involve disseminated sporotrichosis identified through fine needle aspiration cytology (FNAC), representing an uncommon and clinically significant form of a disease that typically remains confined to the skin and subcutaneous tissues. Disseminated sporotrichosis is defined by the presence of lesions across two or more anatomically distinct, non-contiguous sites.[4] It is widely recognized as an opportunistic fungal infection, most frequently affecting individuals with compromised immune systems, including those with HIV, hematologic disorders or diabetes mellitus.[5]

In both cases, the patient had a known history of diabetes, reinforcing the role of immunosuppression as a key risk factor for more aggressive disease progression.

While the gold standard for diagnosing sporotrichosis remains fungal culture and isolation of the Sporothrix schenckii species complex,[5,7] this method is limited by its prolonged turnaround time, often requiring four to six weeks.[6] Such delays can hinder prompt initiation of anti fungal therapy, which is particularly critical in disseminated or severe cases. At culture the colonies appear cream colored , smooth and moist initially which later convert to brown black color as was seen in the present study.[8] At 25°C hyphal filaments with conidia formation, yeast forms showing globose budding forms and cigar like structures at 37°C characteristically define sporotrichosis, the morphology of which is reflected at cytology.[2,8]

FNAC provides a valuable alternative, offering a rapid, minimally invasive, and cost-effective approach for early diagnosis. Although its diagnostic utility in sporotrichosis is traditionally limited due to the sparse presence of fungal elements in tissue samples, the FNAC smears in these cases revealed abundant fungal structures. In a study by Gouda et al.[9], out of 50 cases fungal elements were noted in 20 cases on FNAC whereas culture was positive only in 13 cases. Nevertheless in the study by Chowdhury et al.[4], all 27 cases showed positivity on both cytology and culture highlighting high accuracy of FNAC in diagnosing fungal infections. This finding is more commonly observed in immunocompromised hosts or in infections with high fungal burden, as seen in feline sporotrichosis.

Microscopic examination of the cytological samples revealed granulomatous inflammation, neutrophilic infiltration, and a background rich in cellular debris. Notably, numerous oval, elongated, and cigar-shaped yeast forms were identified both extracellularly and within the cytoplasm of multinucleated giant cells.[3,9] These morphological features are characteristic of Sporothrix species and can be effectively visualized using routine stains such as Giemsa or Papanicolaou, especially when fungal load is high. However, careful differentiation from other encapsulated fungi, including Cryptococcus and Histoplasma remains essential.[5]

The use of adjunctive stains like Periodic Acid-Schiff (PAS) and Gomori methenamine silver (GMS) further enhances the diagnostic accuracy of FNAC as shown in Fig. 4.[5,7] In both cases, early identification through cytology enabled timely initiation of antifungal therapy, resulting in favorable clinical outcomes. These findings underscore the critical role of FNAC in expediting diagnosis and treatment, particularly in rare and severe manifestations such as disseminated sporotrichosis.[7]

Clinically, majority of the cases present as soft tissue swelling, mimicking a benign soft tissue tumor. However disseminated forms may present as ulcerated erythematous nodules or plaques especially in immunocompromised individuals.[1] Common differential diagnosis such as cutaneous tuberculosis, other fungal infections like leishmaniasis and chromoblastomycosis or pyoderma gangrenosum.[4] In the present report, both cases presented with subcutaneous nodules similar to that reported by Amita K et al.[10]

Ethical Considerations

Institutional Ethical Committee approval obtained bearing registration number No. AIMS/IEC/ 522/2026

Informed Consent

Written informed consent was obtained.

References

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