A 35-year-old gentleman of Indian origin, who works as a factory vegetable sorter in London, presented in February 2008 with a two-month history of a painless lump over the dorsum of his right hand. There was no history of trauma, and the patient reported no systemic symptoms. Although the gentleman had emigrated from India 11 years ago, he denied any recent travel. Past medical history and family history were both unremarkable. He subsequently underwent a surgical excision biopsy but was lost to followup.
The gentleman then represented eight months later with recurrence of the previously excised hand swelling but in addition noticed a new painless swelling on the dorsum of his right ankle. Both lesions were functionally asymptomatic and no other systemic symptoms were reported. He was previously well with no past history of other infections.
Clinical examination of the right anterolateral ankle demonstrated an 8 × 5
cm firm, nonfluctuant, nontender lump, which was tethered to deep structures and adherent to the hyperpigmented overlying skin (). The lesion was normothermic and displayed no regional lymphadenopathy.
Nodular appearance of right dorsal hand swelling (a) and foot (b).
His right hand revealed a well-healed midline surgical scar on the dorsal aspect, adjacent to a dorsal-ulnar 6 × 5
cm nodular, soft, fluctuant, yet non-tender lump. Tethering to overlying skin and deep tissues was noted; there was no regional lymphadenopathy ().
Investigations revealed a normal differential white cell count, a normal immunoglobulin levels, and a normal CD4, CD8 cell counts; he tested negative for HIV. No abnormalities were present on biochemical laboratory studies including CRP.
Plain radiographs confirmed no underlying bony abnormality or periosteal reaction. T1 weighted magnetic resonance imaging of the ankle lesion showed a 6 × 2
cm heterogenous soft tissue lesion, with scattered cystic regions, prominent vasculature, and surrounding soft tissue oedema, suspicious of either a vascular malformation or a neoplasm ().
Coronal T1 MRI of right foot large subcutaneous soft tissue lesion anterolaterally (arrow) with a large prominent proximal feeding vessel (arrow).
Retrospective histopathological assessment following the primary excision biopsy confirmed the possibility of a mycetoma, based on the presence of hyphae. A formal microbiological assessment was not conducted on the original specimen and the decision was made to undertake an open biopsy from both lesions, with samples sent for culture and histopathology. Intraoperatively, multiple small black granules were apparent within the region of biopsy ().
Intraoperative photographs of the right hand (a) and the right foot (b) demonstrating multiple black granules.
Samples from both biopsies revealed prominent dark fungal grains in samples from the hand and significantly smaller, less dense, grains from the ankle. Histological analysis of the right hand excision biopsy revealed well-circumscribed fungal colonies (grains) comprising septate dematiaceous hyphae (confirmed by Grocott and DPAS staining), with multinucleated giant cell reaction and Splendore-Hoeppli's phenomenon (). The diagnosis was of a mycotic abscess with acute granulomatous inflammation, consistent with eumycetoma. A sample from the right ankle demonstrated a similar morphological appearance to the hand. Culture yielded a pure growth of two morphologically and colonially distinct molds.
Figure 4 Histological findings on biopsy from the right hand. Multinucleated giant cell reaction (a). Grocott's stain demonstrating branching, septate hyphae (b). MSB stain demonstrating fungal colonies surrounded by a fibrin halo Splendore-Hoeppli's phenomenon (more ...)
Samples from the hand produced small, slow growing, gray, and domed colonies from all inoculum sites. Microscopic examination of tease mounts prepared from these colonies revealed dematiaceous hyphae but no evidence of sporulation, consistent with a presumptive identification of this organism as Madurella grisea.
Microscopic examination of organisms grown from the ankle revealed abundant oval conidia formed terminally on branched long slender annelids, consistent with species of the Pseudallescheria boydii
]. Sequencing of the nuclear ribosomal repeat gene cassette and of the β
-tubulin gene [5
] of this isolate confirmed that it was S. apiospermum
sensu stricto (EMBL accession number FN600642).
Sequences from the organism isolated from the hand lesion (EMBL accession numbers FN600643–FN600645) did not match any in the synchronized public databases but were 100% identical to sequences previously obtained at the UK National Mycology Reference Laboratory (MRL) from isolates of M. grisea infections acquired in the Indian subcontinent (Borman, unpublished data). No mycobacteria were observed in auramine films or on culture.
Based on antifungal susceptibility profiles compiled at the MRL for over 50 isolates encompassing 8 different causative species of dark grain mycetoma, the patient was commenced on the broad spectrum triazole voriconazole. Six months after initiation of voriconazole, there has been complete resolution of the Scedosporium ankle lesion but little change in the Madurella hand lesion.